Download Practice Exam 2

Practice Exam 2
1) When a parachutist jumps from an airplane, he eventually reaches a constant speed, called the terminal
velocity. This is an example of
A) Newton's First Law of motion.
B) Newton's Second Law of motion.
C) Newton's Third Law of motion.
D) All of Newton's laws apply to this situation.
Answer: D
2) A ball is thrown up into the air. Ignore air resistance. When it is rising and reaches half of its maximum
height, the net force acting on it is
A) equal to its weight.
B) greater than its weight.
C) less than its weight, but not zero N.
D) zero N.
Answer: A
3) A person has a mass of 45 kg. How much does she weigh on the Moon, where g = 1.62 m/s2?
A) 45 N
B) 73 N
C) 7.4 N
D) 440 N
Answer: B
4) You ride on an elevator that is moving with constant downward acceleration while standing on a
bathroom scale. The reading on the scale is
A) equal to your true weight, mg.
B) less than your true weight, mg.
C) more than your true weight, mg.
D) could be more or less than your true weight, mg, depending on the magnitude of the acceleration.
Answer: B
5) If the work done to stretch a spring by 4.0 cm is 6.0 J, what is the spring constant?
A) 300 N/m
B) 3000 N/m
C) 7500 N/m
D) 6000 N/m
Answer: C
6) The ratio of power outputs of Jack and Jill is 2:1 to complete a certain amount of work. If Jill takes 4
minutes to complete this work, how long will Jack take to finish the same work?
A) 2 minutes
B) 8 minutes
C) 6 minutes
D) 4 minutes
Answer: A
7) The work done by the centripetal force on an object with a mass of 1 kg moving with a constant velocity
of 4 m/s into a circular path of radius 0.6 m for one full cycle is
A) 100.7 J
B) 3.8 J
C) 0 J
D) 80 J
Answer: C
8) What is the kinetic energy of the mass after the mass is released and it is no longer in contact with the
spring?
A) 0.50 J
B) 0.20 J
C) 5.0 J
D) 10 J
Answer: A
9) A force of 15 N applied to a spring compresses it by 4 cm. What is the potential energy of the spring in
the compressed position?
A) 0.1 Nm
B) 0.2 Nm
C) 0.3 Nm
D) 0.4 Nm
Answer: C
A 2.0-g bead slides along a wire, as shown in Figure above. At point A, the bead is at rest. Neglect
friction and use g = 10 m/s2.
10) What is the kinetic energy of the bead at point B?
A) 0 J
B) 2.0 × 10-2 J
C) 16 × 10-3 J
D) 0.40 J
Answer: B
11) What is the speed of the bead at point B?
A) 10 m/s
B) 4.9 m/s
C) 0 m/s
D) 4.5 m/s
Answer: D
A roller coaster of mass 80.0 kg is moving with a speed of 20.0 m/s at position A as shown in Figure
above. The vertical height at position A above ground level is 200 m. Neglect friction and use g = 10.0
m/s2.
12) What is the total energy of the roller coaster at point A?
A) 16.0 × 103 J
B) 20.2 × 103 J
C) 16.0 × 104 J
D) 17.6 × 104 J
Answer: D
13) Neglecting air resistance, when you toss a stone straight up in the air from Earth's surface, the
following is true for the upward motion of the stone.
A) The stone's kinetic and gravitational potential energies increase simultaneously.
B) The stone's kinetic and gravitational potential energies decrease simultaneously.
C) The stone's kinetic energy decreases while its gravitational potential energy increases.
D) The stone's kinetic energy increases while its gravitational potential energy decreases.
Answer: C
14) Two ice skaters push off against one another starting from a stationary position. The 45-kg skater
acquires a speed of 0.375 m/s. What speed does the 60-kg skater acquire?
A) 0.500 m/s
B) 0.281 m/s
C) 0.375 m/s
D) 0 m/s
Answer: B
15) Two children are riding on a merry-go-round. Child A is at a greater distance from the axis of rotation
than child B. Which child has the larger tangential speed?
A) Child A
B) Child B
C) They have the same tangential speed.
D) There is not enough information given to answer the question.
Answer: A
16) Two children ride on a merry-go-round, George is at a greater distance from the axis of rotation than
Jacques. It is a true statement that
A) Jacques has a greater speed than George.
B) Jacques and George have the same speed.
C) Jacques has a smaller speed than George.
D) Cannot tell which one has the greater speed without knowing their masses.
Answer: C
17) A disk and a hoop of the same mass and radius are released at the same time at the top of an inclined
plane. Which object reaches the bottom of the incline first?
A) The hoop
B) The disk
C) Both reach the bottom at the same time.
D) It depends on the angle of inclination.
Answer: B
18) A satellite completes one full orbit around Earth. The work performed by Earth's gravitational force on
the satellite is
A) always positive.
B) zero J.
C) always negative.
D) positive most of the time.
Answer: B
19) Because Earth's orbit is slightly elliptical, Earth actually gets closer to the Sun during part of the year.
When Earth is closer to the Sun its orbital speed is
A) less than when Earth is farthest away from the Sun.
B) the same as when Earth is farthest away from the Sun.
C) greater than when Earth is farthest away from the Sun.
D) sometimes greater sometimes smaller than when Earth is farthest away from the Sun.
Answer: C
20) A croquet mallet balances when suspended from its center of mass, as shown in the figure (left). If you
cut the mallet in two at its center of mass, as shown, how do the masses of the two pieces compare?
A) The masses are equal.
B) The piece with the head of the mallet has the greater mass.
C) The piece with the head of the mallet has the smaller mass.
D) It is impossible to tell.
Answer: B
21) An ice skater doing a spin pulls in her arms, decreasing her moment of inertia by a factor of two, and
doubling her angular speed. Her final rotational kinetic energy
A) remains unchanged.
B) is cut in half.
C) quadruples.
D) is doubled.
Answer: D