Download and respectively. μ k μ s M1gSin(θ) μ s M1gCos(θ) μ s

For the next three questions consider the following scenario. A block with mass M1 is attached
to a block with mass M2, as shown in the above diagram. Assume the strings and pulley
connecting the two blocks are massless, and frictionless. Additionally the surface of the wedge
has coefficients of kinetic and static friction​ μ k and μ s respectively.
11. If you observe block 2 accelerating downwards, what is the magnitude of the frictional force
felt by block 1.
A) μ sM1gSin(θ)
B) μ sM1gCos(θ)
C) μ kM1gCos(θ)
D) μ k(M1 + M 2)gT an(θ)
E) None of the above.
12. Let us now assume that block 1 was initially at rest, with a net force of 10 newtons pointing
up the wedge. If block 1 has a mass of 2 kg, how long will it take it to travel a distance of 1
meter? (Note: The ramp is sufficiently long that the block will never go over the edge and fall
down).
A)
B)
C)
D)
E)
√2/5 seconds
√1/5 seconds
√2 seconds
1 second
Not enough information was provided.
13. What additional complications might arise if the pulley now has a moment of inertia?
A)
B)
C)
D)
E)
We can no longer assume the two tensions forces are the same.
There may exist a net torque on the pulley.
It is now possible for one block to be accelerating, while the other block is at rest.
Both A and B are correct.
No additional complications arise.
14. Suppose a mass is attached to two ​identical​ springs (both fixed to the wall), as shown
above. Assuming both springs are at their equilibrium positions initially, and have spring
constants k1 = k2 = k , how much work is needed to move the block a distance D to the left.
A) kD2
B) 12kD2
C) 0
D) 14kD2
E) − 2kD
15. For this next problem consider a person with mass M located at the edge of a spinning disk
also with mass M, that has a radius R, and angular velocity
distance of ½ R, what is his final angular velocity?
A) 12 Iω2
B)
C)
ω
2ω
ω ​.
If the person moves to a
D) 34 ω
E) 12 ω
For the next three questions consider the following scenario. Three balls of equal mass M
remain at rest right next to each other on a table. Suddenly, due to some source of potential
energy, one of the balls heads north with a velocity of 4 m/s and the other heads east with a
velocity of 3 m/s.
16. What is the final speed of the 3rd ball?
A)
B)
C)
D)
E)
7 m/s
5 m/s
1 m/s
0 m/s.
Not enough information.
17. Which of the following statements is not true? (Note: The system we shall consider here is
the three balls plus whatever source of potential energy caused them to gain velocities).
A)
B)
C)
D)
E)
Total energy of the system is conserved.
The kinetic energy of the system is not conserved.
Momentum of the system is conserved.
The net force on the ball heading north at all times during this scenario was zero.
All of the above are true.
18. After the ball heading north has traveled 4 meters, what is the magnitude of the position of
the center of mass of the ​remaining two balls​ (with respect to the original position of all 3
balls).
A)
B)
C)
D)
E)
4m
3m
1.8 m
2.7 m
2.0 m
For the next question consider the above diagram. We have two balls with equal masses m and
equal velocities V heading towards a rod of length L and mass M, that is at rest.
19. Suppose both balls reach the rod at the same time. What is the magnitude of the angular
acceleration of the rod, about its center, if the balls each instantaneously exert a force of 20 N
on opposite sides of the rod. (Note: The rod has mass M = 10 kg, and length L = 10 m).
A)
B)
C)
D)
E)
18 rads per second
200 rads per second
12/5 rads per seconds sq
40 rads per second
The net force on the rod is zero, so there is no torque, and hence the rod has no angular
acceleration.
20. Ignore all previous numbers listed in question 19. If both balls stick to the rod at the same
time, what is the final angular momentum of the system about the center of the rod?
A) mLV
2
B) mLV
12
C) 2mLV
D) M LV
E) None of the above.