Dynamics and Torques

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Using a pencil, answer the following questions. The lab is marked based on clarity of responses,
completeness, neatness, and accuracy. Do your best! Please ensure that any data measured (or recorded)
includes the appropriate number of significant digits (only one uncertain digit).
This activity is divided into three sections:
• Core – this first section explores only the basic “core” ideas involved in understanding. Students must demonstrate a
sound understand with all of their answers in this section BEFORE attempting the next section.
• Mastery – Your instructor will NOT review this section if the Core section above shows any misconceptions. In this
section students will make predictions and apply the concepts and ideas learned above. For complete mastery it is
expected that data collection and scientific procedures will be as accurate as possible. All work shown should be clear
with any units included. Answers should be rounded off to the correct number of significant figures based on the data
collected.
• Ace – Once again, your instructor will only look at this section provided he/she is confident that the above Mastery
criteria has been met. In this section students will demonstrate a deeper understanding of the concepts through error
analysis, experimental design etc. Physics concepts from other units already covered will often be required here.
Objectives:
• To construct a free body diagram showing all forces (gravity and tension)
• To develop an equation for the net force on the entire system of objects, or on a single object
• To determine, graphically, the gravitational field strength, g
Description: (open the sim below)
http://higheredbcs.wiley.com/legacy/college/halliday/0471758019/simulations/sim20/sim20.html
The simulation shows two masses connected by a cord passing over a pulley. You can control the size of
each mass and the simulation will calculate the acceleration of the system, the force of gravity acting on
each mass, and the tension in the cord. The effects of friction and the mass of the pulley can be ignored
(leave as Pulley has no mass).
UNIT 02: Dynamics and Torques BCLN PHYSICS 12 – Rev. Nov, 2016
Page 2 of 14
Part 1: Core
Label all forces acting directly onto the diagram above. Be sure to identify mass1 and mass2 with
appropriate subscripts.
1. Open the simulation file ‘Atwood’s Machine’ and experiment with the size of each mass, then
answer the questions below.
• The mass of the blocks can be set to whole numbers between 0 kg to 10 kg. What values for m1
and m2 yield the maximum tension? How does the tensions in the rope compare to the weight of
each mass?
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
UNIT 02: Dynamics and Torques BCLN PHYSICS 12 – Rev. Nov, 2016
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• With the same mass configuration as above you should see that one block’s weight pulls the
system counter-clockwise, while the other pulls on the rope (with the same magnitude) clockwise.
Why is the tension not double what it shows? Show how this would violate Newton’s Laws by
isolating one block only to examine the forces.
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
• Set both masses to 5 kg. What is the tension in the rope? _________________. How does this
compare to the weight (force of gravity) acting on each mass? __________________
• What is the Net Force acting on the entire system? Show equation and magnitude.
FNET = ____________________ = _______ N
• Now reduce the mass on the left by 1 kg (4 kg mass on the left with a 5 kg mass on the right).
Complete the free body diagrams below with appropriate labels and answer the questions:
Left Mass: Right Mass:
Direction of the Net Force? UP/DOWN? (circle)
Place the magnitude of the values for both the
tension, FT , and the weight, Fg directly onto the
diagram.
Complete the inequality (use <, ≤, =, ≥, or >)
FT ________________ Fg
Explain why this makes sense based on what
happens when you run the simulation.
Direction of the Net Force? UP/DOWN? (circle)
Place the magnitude of the values for both the
tension, FT , and the weight, Fg directly onto the
diagram.
Complete the inequality (use <, ≤, =, ≥, or >)
FT ________________ Fg
Explain why this makes sense based on what
happens when you run the simulation.
UNIT 02: Dynamics and Torques BCLN PHYSICS 12 – Rev. Nov, 2016
Page 4 of 14
• Based on your findings above, what must be true for the possible value of the tension in the rope?
In other words, the tension must lie between what two values?
______________________________________________________________________________
______________________________________________________________________________
Now let’s examine the entire system.
2. You have seen in tutorials that one way to imagine this system is to stretch it out so that all of the
forces act on a single plane (like dragging blocks along a table). Set the masses to the values
shown below, complete the diagrams and determine the equations of motion.
Original Set Up (Trial 1) “Stretched Out” (Trial 1)
Equation of Motion:
FNet = ______________________________ = ___________ N
Solve for acceleration:
a = ____________ m/s2
UNIT 02: Dynamics and Torques BCLN PHYSICS 12 – Rev. Nov, 2016
Page 5 of 14
Original Set Up (Trial 2) “Stretched Out” (Trial 2)
Equation of Motion:
FNet = ______________________________ = ___________ N
Solve for acceleration:
a = ____________ m/s2
3. Explain, with reference to Newton’s Laws, how it is possible for the above two systems to have
the same Net Force, yet different accelerations.
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
UNIT 02: Dynamics and Torques BCLN PHYSICS 12 – Rev. Nov, 2016
Page 6 of 14
4. Set up the systems shown below and complete the table:
Original Set Up (Trial 1) “Stretched Out” (Trial 1)
Equation of Motion:
FNet = ______________________________ = ___________ N
Solve for acceleration:
a = ____________ m/s2
Original Set Up (Trial 2) “Stretched Out” (Trial 2)
Equation of Motion:
FNet = ______________________________ = ___________ N
Solve for acceleration:
a = ____________ m/s2
UNIT 02: Dynamics and Torques BCLN PHYSICS 12 – Rev. Nov, 2016
Page 7 of 14
5. Explain, with reference to Newton’s Laws, how it is possible for the above two systems to have
the same acceleration, yet different Net Force.
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
Summarize:
6. Two different Atwood Machines are set up with different masses on each machine. Machine one
has masses m1 and m2, while machine two has masses m3 and m4. Both machines have the same
Net Force for the entire system (consider all masses moving as one). What must be true of the
masses to be able to claim this?
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
7. Two different Atwood Machines are set up with different masses on each machine. Machine one
has masses m1 and m2, while machine two has masses m3 and m4. Both machines have the same
acceleration for the entire system (consider all masses moving as one). What must be true of the
masses to be able to claim this?
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
Data Collection:
Start both masses at 5kg each. Record the acceleration into the table. Reduce one mass by 1kg and add
1kg to the other maintaining a total mass of 10kg. Continue this process to complete the data table
whilst maintaining a constant total mass of m1 + m2 = 10kg.
Table 2: Atwood’s Machine with massless pulley
red mass, m1
(kg)
blue mass, m2
(kg)
Acceleration, a
(m/s2
)
Fnet (system)
Calculate for Graph 1
x-axis for Graph 2
define:
____________
5 5 0
4 6
UNIT 02: Dynamics and Torques BCLN PHYSICS 12 – Rev. Nov, 2016
Page 8 of 14
Analysis:
1. Use Newton’s Second Law to determine our Fnet equation. Your final equation should only
include Fnet, m1, m2, and a.
Fnet = _______________________________
2. Plot a graph of Fnet (system) versus acceleration, a. Be sure to add appropriate titles and axis
labels.
Graph 1: Fnet vs a
3. Determine the slope of your graph. Include any units.
Slope = rise/run = Δy/Δx = ΔFnet/Δ( ______ ) = ____________
4. Determine the equation of your line using slope-intercept form: Don’t forget to include units for
any constants.
Equation of line : _________________________
UNIT 02: Dynamics and Torques BCLN PHYSICS 12 – Rev. Nov, 2016
Page 9 of 14
5. Describe precisely what the slope of your graph represents. Support your answer with the
equation of motion determined in question (1) above.
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
Part 2: Mastery
Analysis:
1. Rewrite the equation of motion in the space below (determined above in “Analysis” question (1))
Your final equation should only include m1, m2, a, and g. (hint: start with Fnet = ma = ∑F)
_______________________________
2. Solve the equation above for acceleration, a. Simplify the equation as much as possible by
factoring out any constants. Circle everything that remains constant on the right hand side of the
formula (don’t forget the main condition for the two masses described above your data table).
a = _________________________
3. Create a straight line graph based on your equation above. The y-axis will be one variable
(acceleration, a), the x-axis will be the other variable (everything BUT the constants that you
circled. This can be a simple formula. Once you have determined what goes onto the x-axis, add
this variable to the last column of your data table and calculate values for each row. Be sure to
label the graph properly.
x-axis = __________________
UNIT 02: Dynamics and Torques BCLN PHYSICS 12 – Rev. Nov, 2016
Page 10 of 14
Graph 2:
4. Determine the slope of your graph. Include any units.
Slope = rise/run = Δy/Δx = Δa/Δ( ______ ) = _____________
5. Determine the equation of your line (slope intercept form with appropriate variables). Don’t
forget to include units for any constants.
Equation of line : _________________________
6. Describe precisely what the slope of your graph represents. Support your answer with the
equation determined in question (2) above.
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
UNIT 02: Dynamics and Torques BCLN PHYSICS 12 – Rev. Nov, 2016
Page 11 of 14
7. Using the value obtained for your slope, along with your answer to question (6) above, determine
the value of “g”. DO NOT simply plug in masses and determine “g” from one arrangement of
masses. You are to use your slope along with any constants (or experimental controls) only.
Show all steps.
g = _______________
UNIT 02: Dynamics and Torques BCLN PHYSICS 12 – Rev. Nov, 2016
Page 12 of 14
Part 3: Ace
On the simulation select “Pulley mass = 2 kg”.
Repeat the first experiment found in Part 1:
Start both masses at 5kg each. Record the acceleration into the table. Reduce one mass by 1kg and add
1kg to the other maintaining a total mass of 10kg. Continue this process to complete the data table
whilst maintaining a constant total mass of m1 + m2 = 10kg (plus the additional contribution of the 2kg
pulley)
Table 2: Atwood’s Machine with pulley = 2kg
red mass, m1
(kg)
blue mass, m2
(kg)
Acceleration, a
(m/s2
)
Fnet (system)
Calculate for Graph 1
5 5 0
4 6
1. Plot a graph of Fnet (system) versus acceleration, a. Use the axis already set up in Part 1 (Graph
1). Add this new line and label it “with 2 kg pulley”.
2. Determine the slope of your graph. Include any units.
Slope = rise/run = Δy/Δx = ΔFnet/Δ( ______ ) = ____________
3. Determine the equation of your line using slope-intercept form: Don’t forget to include units for
any constants.
Equation of line : _________________________
4. In Part 1 you were asked to discuss the significance of the slope you found. Hopefully it was
concluded that your slope was equivalent to your overall mass, m1 + m2, since this value
remained constant. Does your new graph have a larger or smaller slope? _______________ .
How does this slope compare to the new overall mass of the moving system (including the
pulley)? __________________________
UNIT 02: Dynamics and Torques BCLN PHYSICS 12 – Rev. Nov, 2016
Page 13 of 14
5. We often refer to Newton’s Second Law as an extension to his First Law (the law of inertia). In
fact, if we write the second law as ?⃑ = ???? ����������⃑
? , we could say that as the mass of a system increases,
the acceleration decreases. Examine your two data tables (Table 1 from part 1 and Table 2
above). Does this seem to be true? What happens to the acceleration if the mass of the pulley
contributes?
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
6. Discuss why the additional mass of the pulley might not affect the overall mass of the system as it
did with the hanging masses (i.e We cannot simply find the value of the acceleration using
?⃑ = ???? ����������⃑
? , where Fnet = Fg2 – Fg1 and m = total mass of system). How is the pulley different from
the hanging masses?
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
7. Mass is defined as a “measure of an object’s inertia”. The bigger the mass, the stronger the
tendency to resist changes in motion (First Law). Pulley’s also have inertia and want to resist
changes in rotation. Look up rotational inertia, or moment of inertia, I. What is the general
definition for Moment of Inertia?
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
8. The most general expression for calculating the Rotational Moment of Inertia is ? = ∑ ??2. Use
this equation to help discuss how an object’s resistance to rotating, I, depend not only on its mass,
but also how the mass is distributed. Provide an example that illustrates how the position (or
distribution) of the mass can change how easily something can be set into rotation.
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
UNIT 02: Dynamics and Torques BCLN PHYSICS 12 – Rev. Nov, 2016
Page 14 of 14
9. Finally, isolate just the pulley and label all forces acting on the pulley.
Free Body Diagram – Pulley of mass 2 kg on Atwood’s Machine
10. Why must the tensions be different if we want the pulley to spin?
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________

Sample Solution

As indicated by study performed by Jeffrey A. Frankel, 2005 swapping scale is characterized as the cost of remote money. For example, the swapping scale between Malaysian Ringgit and Dollar is commonly communicated in dollar per Ringgit ($/RM). The conversion standard acts a significant job in the nation economy development and effectively being influenced by the economy emergency. Since free of the Malaysia in 31st August 1957, the nation has confronted and experienced four significant emergencies. The main emergency is in 1971 to 1973 in light of the fact that the finish of the Bretton Woods System and the oil emergency. The subsequent emergency occurred in 1980 to 1981 because of the decrease in ware costs together with the second oil emergency. Pursued by the third emergency somewhere in the range of 1985 and 1986 because of the electronic emergency. The fourth situation occurred during 1997 and 1998 because of money related emergency (Ming-Yu Cheng and Sayed Hossain, 2001). The budgetary emergency has given tremendous effect on the nation monetary development and along these lines contact the nation’s conversion scale. In spite of the fact that, deterioration of the Malaysia’s money has upsides and downsides, the present situation has perceived that the debilitating of Ringgit on the planet showcase brings about more negative than positive outcomes particularly to residents. Hence, it is basic for us to distinguish and comprehend the assurance of conversion standard and the impact to the state, with the goal that we can control the unpredictability of swapping scale and abbreviate the effect to the country.

DETERMINANTS OF VALUE OF RINGGIT

We separated the variables adding to the estimation of Ringgit in three areas. Right off the bat, the financial components, besides, the politic variables and in conclusion the outer elements of the Ringgit.

Financial FACTORS

Loan fee

As per Kevin James, 1998, one of the approaches to draw in outside direct speculation or capital inflow is by expanding loan fee of the nation. High loan fee infers that the financial specialist will increase high benefit from their venture, henceforth this will pull in more speculator to put resources into our state. As a result, the nation parity of installment will be in surplus and the nation money will start to revalue. This show financing cost and swapping scale are emphatically related, higher loan cost can prompt the gratefulness estimation of the Ringgit while low loan fee will prompt devaluation estimation of Ringgit. As per look into performed by Hans Jarle Kind and Mohd Nazari Ismail, 2001, expansionary financial arrangement by government will make the interest for cash and consequently add to increment in loan cost of the nation. At the point when loan cost rises, the nation cash will start to acknowledge too. Though, when government increment the duty toll to open, the nation utilization will all the while decline, in this manner financing cost of the country prone to diminish, this last will bring about the discrediting of the nation cash.

Expansion

As per Elizabeth Chua Siew Eng and John G. Bauer, another component that can influence the Malaysia swapping scale is swelling. High expansion will make the nation money to depreciate, while low swelling will give positive effect to the nation by acknowledging in nation cash. In 1970s, Ringgit has acknowledged against the US Dollar in light of the higher expansion in the US when contrasted with Malaysia. In late 1991 and mid 1992, Bank Negara Malaysia (BNM) approach of battling swelling by a stringent money related arrangement results in higher financing cost along wirh huge capital inflow to the nation. This had made the Ringgit appreciate. Increments in charge forced on nitizen of the country will probably make the spending reduce in view of higher expansion. For example, when the administration of Malaysia forced GST (great and administrations part) in April 2015, retail spending or utilization decay since obtaining intensity of the individuals decline. As illustrated, the offers of European brands in car division have recorded colossal drop when the GST is being visited. GST additionally anticipated to make swelling come to fruition in Malaysia. Legislative leader of Malaysia Central Bank, Tan Sri Dr Zeti Akhtar Aziz likewise perceives that GST will cause swelling.

Capital Inflow

Capital inflow is the factor to decide the estimation of Ringgit. This wonder can be seen during Asian emergencies somewhere in the range of 1997 and 1998. It was not originating from neither skewed trade rates, mixed up household approach, nor absence of straightforwardness in the financial area, yet it was endlessly ascribed to a blend of an unreasonably quick ascent of capital inflows just as the falling worldwide interest for the fares from the district that emerged from a worldwide economy. This view bolstered by Fumitaka Furuoka, Beatrice Lim, Catherine Jikunan and Lo May Chiun. Disdain of this emergency, they demonstrate that it changing the commercial center rule that leads Ringgit to deteriorate. As per Ooi Sang Kuang, in the initial five months of 2006, in view of the great financial crucial by the legislature of Malaysia, for example, new speculation impetus bundles and further progression of outside trade organization measures and furthermore the arrival of Ringgit pegged to US Dollar, capital inflows is generally expanding and Ringgit is refreshing contrasted with US Dollar by 5.5% coming to the most elevated in May by 3.5825. Additionally, in 1986 in view of the inflow of outside trade to Malaysia because of fare and remote direct venture and furthermore due to the exchange shortage US, Malaysian Ringgit shows thankfulness pattern contrasted with USD (Elizabeth Chua Siew Eng and John G. Bauer). The most noticeably terrible money related emergency occurs after autonomy began in mid-1997 when the capital inflows occur in Malaysia. For the most part, capital inflows will upgrade the pace of financial advancement, in any case, in Malaysia case; it alters the recognition on nation’s monetary possibilities. It misfortunes of trust in Malaysia’s capacity to go up against the difficulties ahead include the monetary presentation. It swell out when there is an unexpected withdrawal of momentary capital from the nation and pursued by Thai’s Bath gliding in July 1997(Cheng and Sayed, 2001). As indicated by Cheng and Sayed (2001), this withdrawal has made vulnerability and unpredictability in the outside trade and value commercial centers. They underscore that hysterical speculators began to extricate out the overwhelming size of transient capital, which bringing about a sharp devaluation of money and lift the financing costs.

Financial specialists Speculation

Before Asian Financial Crisis 1997, Malaysian Ringgit is solid in view of Malaysia’s solid exchange position. This made Bank Negara to have a strategy not to help the conversion standard, however to look after it. Sadly, Ringgit has been assaulted by outside financial specialist examiner (Dr. Tarek H. Selim), because of that, Malaysian Ringgit encountered an immense loss of money. As per Gale Raj, Yanice Colón, Silvana Kostembaum and Robert Cordova, as outsiders hold a huge Ringgit as a result of high seaward loan fee, it built up liabilities for the Malaysian financial framework. In this manner, potential seaward theorists need more money to destabilize the Malaysian financial framework. Be that as it may, when the monetary emergency began, much theoretical weights occurs in Malaysia which cause to an expansion of Ringgit credit requests, rose of momentary loan cost, advancing weight on the money, and makes immense capital outpourings that naturally prompts devaluation of Ringgit.

POLITIC FACTORS

Political Stability

Political dependability additionally is one of the segments that impact the estimation of the Ringgit. As indicated by Saleena Saleem (2015), the political emergency in Malaysia can intensify the financial condition whereby solid and trustworthy initiative is essential to empower speculator and purchaser trust. There is term in political factor as expressed by Nordhaus (1975), refered to by Pepinsky (2007), “Political business cycles (PBCs) are politically instigated variances in monetary pointers, for example, spending, joblessness, swelling that relates to a nation’s constituent cycle”. Current questionable issue of 1 Malaysia Development Berhad (1MDB) embarrassment has revealed debilitating the estimation of the Ringgit.

Absence of straightforwardness in IMDB examination has expanded the capital outpouring coming about because of a decreasing number of financial specialists that end up impacting Ringgit. In July 2015 when the IMDB allegation against the Prime Minister, Najib Razak, Malaysia’s remote stores fell by about 5% of national bank when they flopped trying to continue the Ringgit RM3.80 per US dollar in about fourteen days (Saleena Saleem, 2015). Exacerbate it; there is a sharp fall in remote stores parallel to exposure over 1MDB issue. Malaysia’s outside stores presently remain beneath US$100 billion, raising feelings of trepidation over its capacity to prepare for further money stuns. Money related investigators likewise propose that capital surges will keep adding to advance Ringgit debilitating (Saleena Saleem, 2015).

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