Physics 152 practice exam

PRACTICE EXAM 2B – PHYS 15200 Part I. Multiple Choice Questions [2 pts each]
Directions: Choose the alternative that best completes the statement or answers the question. Unless otherwise stated, assume ideal conditions (no air resistance, uniform gravity, etc.)

! !
!
!
ˆ
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1) Let A = !3i + 4 ˆ and B = i + 2 ˆ . What is A • B ? j j
(A) 3
(B) 5
(C) 8
(D) None of these.
2) A particle moving along the x axis has a potential energy given by the function U(y) = -5x4, where x is in meters and U is in joules. What is the x-component of the force acting on the particle at x = 2 m?
(A) -160 N
(B) -80 N
(C) 160 N
(D) None of these.
3) A railroad tank car contains milk and rolls at constant speed along a straight level track. The milk begins to leak out the bottom. The car’s forward momentum then
.
(A) increases.
(B) decreases.
(C) remains the same.
(D) Not enough information.

4) A bowling ball strikes an upright bowling pin. The bowling ball has three times the mass of the pin.
Which experiences the greater change in speed as a result of the collision?
(A) Ball.
(B) Pin.
(C) Same change in speed.
(D) Not enough information.
5) A satellite is in a circular orbit of radius r about the Earth. Let the magnitude of the force of gravity acting on the satellite due to the Earth equal F. What is the correct expression for the work done by gravity on the satellite?
(A) 0
(B) F(2πr)
(C) F(πr2)
(D) None of these.

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PRACTICE EXAM 2B – PHYS 15200 Part II. Word Problems [30 pts each]
Directions: Solve each problem. Do not write on the formula sheet. Show your work to receive full credit.
Box your final answer and record its appropriate unit. Unless otherwise stated, assume ideal conditions
(no air resistance, uniform gravity, etc.)

PROBLEM 1
A rocket (mass 3M) traveling east at 100 m/s suddenly explodes into two pieces. Piece 1 (mass M) has a velocity of 200 m/s at 40° north of east. Piece 2 has a mass 2M.
(A) What is the magnitude of Piece 2’s velocity immediately after the explosion?
(B) What is the direction of Piece 2’s velocity immediately after the explosion? Express your answer as an angle measured south of east.

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PRACTICE EXAM 2B – PHYS 15200 PROBLEM 2
20
g

100 g 5.0 m/s

A 20-gram block slides at 5.0 m/s toward a 100-gram block, which is initially at rest. After the blocks have an elastic collision, the 100-gram block slides to the right into a horizontal spring of constant 30
N/m. Assume that the horizontal surface is frictionless and the right end of the spring is attached to a wall. (A) What is the speed of the 100-gram block immediately after the collision?
(B) What is the maximum compression of the spring?

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PRACTICE EXAM 2B – PHYS 15200 PROBLEM 3
F

37° A woman pulls her 20-kg bobsled at constant speed up a 10-meter long ramp sloped at 37° to the ground.
She pulls with a constant force of magnitude F parallel to the ramp. The coefficient of kinetic friction between the ramp and the bobsled is 0.25.
(A) What is the magnitude F of her pulling force?
(B) What is the work done by the woman in pulling the bobsled up the entire length of the ramp?

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