PHY 111 Final Exam Multiple Choice Questions and Correct Answers.

PHY 111 Final Exam Multiple Choice
Questions and Correct Answers
Question 1
A pendulum with a mass of 1.0 kg and a rope length of 0.5 m is angled at 15° relative
to the vertical. What is the pendulum's period of oscillation once it is released?
Correct Answer
1. T= 2pi*sqrt(length of penendulum/g)
length of penendulum= 0.5mCos(15)
length= 0.48m
2. T= 2pi(sqrt(0.48m/9.8))
T= 1.4 s



Question 2
A baseball bat collides with a 0.145 kg baseball moving with an initial velocity of 35
m/s to the left. If the collision lasts 0.005 seconds and the final velocity of the ball is
25 m/s to the right, what was the force of the bat on the ball?
Correct Answer
1. J= F*(change in t)
2. m(vf-vi)=F*(change in t)
3. F= m(vf-vi)/(change in t)
4. F= 0.145[(25-(-35)]/0.005
5. F= 0.145(25+35)/0.005
6. 1740N




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,Question 3
Examine the position vs. time graph for an oscillating object below. What is the period
of oscillation?




Correct Answer
1.5s
-just see how long it takes for a complete wave (3.5,0) (1.5,3.5)



Question 4
What is the buoyant force on a sphere that has half its volume submerged in water
(density = 1000 kg/m3) if the radius of the sphere is 0.1 m? (Vsphere = 4/3πr3,
SAsphere = 4πr2)
Correct Answer
1. Fb= 2/3pg(pi*r^3)
Fb= 2/3(1000)(9.8)(pi)(0.1^3)
Fb= 21 N



Question 5
Which of the following is an example of an oscillating object
Correct Answer
all
-The vibration of a string
-A guard marching back and forth between two points
-A child swinging on a swing set




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,Question 6
A bug splats against the windshield of a car traveling at high speeds down a
backcountry road. Which statement correctly compares the objects' changes in
momentum?
Correct Answer
The bug's change in momentum is equal to the car's change in momentum.



Question 7
A solid 50 kg disk (I = ½ mr2) with a radius of 0.7 m rotates from rest to a final
angular velocity of 20 rad/s in 4.0 seconds. What is the disk's angular acceleration?
Correct Answer
1. change in w=wf-w0
change in w= 20 rad/s-0 rad/s
change in w= 20 rad/s
2. a=change in w/change in t
a= 20rad/s/4.0s
a= 5 rad/s/s



Question 8
A student sets a 0.4 kg meter stick to pivot at the 0.8 m mark. At what position should
the student suspend a 0.2 kg mass to keep the system in static equilibrium?
Correct Answer
Not possible at any position (Static equilibrium cannot be maintained with these
conditions.)



Question 9
Which of the following changes will result in a larger frequency for an oscillating
spring-mass system?
Correct Answer
An increase in the spring constant




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, Question 10
What depth of water (density = 1000 kg/m3) will result in a fluid pressure of 5000 Pa?
Correct Answer
1. h=Pfluid/p(g)
h= 5000Pa/1000(9.8)
h= 0.5m



Question 11

Two students stretch a rope between them. One student oscillates her hand up and
down with a frequency f creating a series of transverse waves that travel down the
rope. Which of the following is a likely outcome if the student doubles the hand
oscillations to 2f?

Correct Answer
The wavelengths of the transverse waves will halve.



Question 12
A student uses a lever to lift a massive object. The student finds that she has to apply
a very large force. Which of the following changes will allow the student to use a
smaller force while still lifting the object?
Correct Answer
The student should angle the force so that it is perpendicular to the lever.



Question 13
A spring-mass system is allowed to oscillate vertically. The period of oscillation is
measured as T. The system is then brought into a low orbit around the Earth.
Compare the new period of oscillation to the original.
Correct Answer
The new period is the same as the original.




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