Download Liang`s first semester Physics final practice

Liang's first semester Physics final practice
Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
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1. How many kilometers are there in one meter?
a. one-millionth
b. one-thousandth
c. one-tenth
d. one thousand
e. none of these
2. During a test of passing ability, a car is able to maintain a uniform acceleration of 3.0 (km/h)/s. How long will it
take this car to increase its speed from 70 to 110 km/h?
a. 7.5 x 10-2 s
b. 1.3 x 101 s
c. 3.7 x 101 s
d. 1.2 x 102 s
e. none of these
3. Which of these has zero acceleration?
a. An object that remains at rest.
b. An object whose velocity is constant.
c. When the average velocity during finite time intervals is always equal to the instantaneous
velocity.
d. All of these.
e. None of these.
4. A peregrine falcon can achieve a velocity of 80 m/s during its dive. If we assume a uniform acceleration of 9.8
m/s2 downward as the falcon free-falls and that the bird was
hovering and not moving at the start of its
dive, how far must it fall to achieve this velocity?
a. 8.2 m
b. 41 m
c. 3.3 x 102 m
d. 6.6 x 102 m
e. None of these
5. The acceleration due to the moon's gravity at its surface is less than what it is here on the surface of the earth.
The computed value of 1.6 m/s2 is consistent with what the Apollo Program astronauts observed during their
explorations there. Imagine an astronaut holding a piece of moon rock over the rim of a crater. At time zero the
rock is 50 m above the crater floor and is tossed upward at 5.0 m/s. How fast will this rock be moving 1.5 s
later?
a. 1.1 m/s
b. 2.4 m/s
c. 2.6 m/s d. 7.4 m/s e. none of these
6. Vector A has magnitude of 2.0 in the +x direction. Vector B has a magnitude of 1.5 and is in the -y direction.
What is the magnitude and direction of B - A ?
a. 0.5 in the -x direction
b. 2.5 and next to the +x axis but 37 degrees above it.
c. 2.5 and next to the +x axis but 37 degrees below it.
d. 2.5 and next to the -x axis but 37 degrees below it.
e. None of these are correct.
7. A vector whose magnitude is 5.0 has been sketched below. What is the x-component of this vector?
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a. 2.5
b. 3.5
c. 4.3
d. 5.0
e. None of these is correct.
8. Two displacements have been described by their components. They are:
Displacement # 1
Displacement #2
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9.
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200 m east and 300 m north
400 m east and 500 m south
Which has the largest magnitude?
a. Displacement # 1
b. Displacement # 2
c. Displacement # 1 plus Displacement # 2
d. The x-component of Displacement #2.
e. None of these are correct.
Consider a golf ball's motion on the moon. There will be no atmosphere to inhibit its motion, so the horizontal
velocity will be constant while there will be an acceleration of only 1.6 m/s2 downward. After being struck by a
golf club, a ball leaves the tee at a velocity of 40 m/s at an angle of 30 degrees above the horizontal. What will
be the ball's velocity 5.0 s later?
a. 32 m/s
b. 20 m/s horizontally and 27 m/s upward
c. 35 m/s horizontally and 12 m/s upward.
d. 35 m/s horizontally and 28 m/s upward.
e. None of these are correct.
A diver leaps from the top of a 36.0 m high cliff, but must also clear a band of rocks that extend 6.0 m out from
the cliff base. Assuming free fall after the diver leaps horizontally, what must be the magnitude of the diver's
velocity at the start of this leap?
a. 0.82 m/s
b. 2.2 m/s
c. 11. m/s
d. 13. m/s
e. 27. m/s
If an archerfish can spit and hit prey as far as 1.2 m directly above it, what is the maximum height at which it
can hit prey when it spits at a 30o angle above the surface of the water?
a. 0.30 m
b. 0.60 m
c. 0.90 m
d. 1.2 m
e. 2.1 m
If the Sun's mass is expressed as 2.0 x 1030 kg and the Jupiter's mass is 1.9 x 1024 kg, the Sun's mass is how
many times greater than Jupiter's?
a. 9.5 x 10-7
b. 1.1 x 101.25
c. 1.1 x 106
d. 3.8 x 1054
e. None of these.
____ 13. Assuming an average mass of 10-26 kg for its atoms, an animal that is composed of about 1029 atoms is most
likely to be a fully-grown, normal:
a. Horse.
b. Human.
c. Chicken.
d. Bacterium.
e. Blue whale.
____ 14. A train is moving at a constant 3.0 x 101 m/s. After noticing the 3 km mark, a commuter starts her stopwatch as
she passes the 4 km mark. What will the stopwatch read when she reaches 5 km?
a. 0.033 s
b. 30. s
c. 33. s
d. 1.7 x 102 s
e. none of these.
____ 15. As a train is moving steadily at 3.0 x 101 m/s past the 5 km mark, the engineer gets ready to apply the brakes
precisely at the 6 km mark. The brakes are set to produce a constant acceleration of -.40 m/s2.
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How fast will the train be moving 50 s after the brakes are applied?
a. -2.0 x 101 m/s
b. 1.0 x 101 m/s
c. 2.0 x 101 m/s
d. 5.0 x 101 m/s
e. none of these
The acceleration due to the moon's gravity at its surface is less than what it is here on the surface of the earth.
The computed value of 1.6 m/s2 is consistent with what the Apollo Program astronauts observed during their
explorations there. Imagine an astronaut holding a piece of moon rock over the rim of a crater. At time zero the
rock is 50 m above the crater floor and is tossed upward at 5.0 m/s. How high above the starting point will this
rock rise before it stops moving upward?
a. 1.3 m
b. 1.6 m
c. 7.5 m
d. 7.8 m
e. none of these.
An object is at the 10.0 m mark and moving away from zero at 3.0 m/s when it experiences a constant
acceleration of 4.0 m/s2 in the same direction that it is moving. How fast will it be moving 5.0 s after the
acceleration begins?
a. 3.0 m/s
b. 19 m/s
c. 20 m/s
d. 23 m/s
e. none of these
In a demonstration here in class, a 1.00 kg mass has been suspended from a thread. An identical thread is tied to
the bottom of the mass. This thread has an actual breaking strength of 10 newton. To break only the lower
thread, one should:
a. push upward on the lower thread.
b. pull down on the lower thread with a quick, firm jerk.
c. pull down on the lower thread with a gentle and slowly increasing force.
d. All of these have the same effect.
e. do none of these.
A person suffered a leg fracture after leaping off a balcony. A net force of at least 2.0 x 105 N must have been
exerted on the person to break the bone. If their mass is 50 kg, what was their acceleration?
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a. 2.5 x 10-4 m/s2
b. 9.8 m/s2
c. 4.0 x 10 3 m/s2
d. 1.0 x 10 7 m/s2
e. None of these.
At a basketball camp during a vertical leap measurement, an 80 kg athlete is able to achieve an upward
acceleration of 7.0 m/s2. This means that during this leap they are pushing against the floor with a force of:
a. 2.2 x 10 2 N
b. 5.6 x 10 2 N
c. 7.8 x 10 2 N
d. 1.3 x 10 3 N
e. none of these.
A rock has been tossed straight upward in this room. What is the net external force acting upon the rock when it
is has reached the highest point in its path?
a. Zero.
b. (m g) and upward.
c. (m g) and downward.
d. More than (m g) and upward.
e. More than (m g) and downward.
A normal force is:
a. perpendicular to a surface.
b. an average, ordinary force.
c. directed in the direction of the acceleration.
d. one that can be understood, instead of one like the Coriolis force.
e. none of these
Consider a 20 kg child who exerts a force of 10 N for 4.0 s during play. How much work is done as the child
exerts this force while pushing straight ahead on a toy car that moves forward a distance of 0.80 m?
a. Zero.
b. 2.0 N.m/s
c. 8.0 N.m
d. 7.8 x 102N.m
e. none of these.
A net force of 2.0 x 101 N is exerted through a distance of 30 m on a 40 kg object. If the object was initially at
rest, how fast is it moving at the end of the 30 m?
a. zero
b. 5.5 m/s
c. 15 m/s
d. 30 m/s
e. none of these
A 2.0 kg mass is being lifted through a vertical height of 3.0 m in 12 s.
To DOUBLE the increase in PEg in this operation one could:
a. double the mass to 4.0 kg and do not change anything else.
b. double the height to 6.0 m and do not change anything else.
c. double the time to 24.0 s for each lift and do not change anything else.
d. either a or b.
e. either a or b or c.
A 20 kg child is swinging on a swing. If she is released from rest at a point 0.80 m above the lowest point in the
swing's path, assuming little friction or air drag, her speed at the lowest point of her path shall be:
a. 2.0 m/s
b. 2.8 m/s
c. 4.0 m/s
d. 16 m/s
e. none of these
During a sprint up a flight of stairs, a person can approach 1 hp. Consider a mountain climber who is ascending
quite rapidly at 200 m per hour in terms of their elevation. If this is a 60 kg person, the average power output
associated with their PEg during this climb is:
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a. 1.4 W or 0.0018 hp.
b. 3.3 x 101 W or 0.044 hp.
c. 2.0 x 103 W or 2.6 hp.
d. 1.2 x 105 W or almost 160 hp.
e. No, it will still be at 1 hp, which is a person's maximum.
The direction for the centripetal acceleration for mud clinging to a rotating tire will be:
a. in toward the axle along a radius.
b. out away from the axle along a radius.
c. parallel to the axle and toward the center.
d. tangent to the tire and in a forward direction.
e. tangent to the tire and in a direction opposite to the motion.
A spacecraft traveling around the Sun along the Earth's orbit but FASTER than Earth:
a. would have a greater acceleration than the Earth.
b. would have a smaller acceleration than the Earth.
c. would still have the same acceleration as the Earth.
d. any of the above, depending upon how much faster it moved
e. None of these are correct.
During sharp turns of their highly maneuverable planes, fighter pilots can be subjected to 'high g' loads, large
acceleration values. Consider an acceleration of 50.0 m/s 2 or a little more than five g. A pilot wants to complete
a turn with a centripetal acceleration of 50.0 m/s 2 while flying at a speed of 300. m/s. The radius of the turn
should be:
a. 5.56 x 10 -4 m.
b. 6.00 m.
c. 1.8 x 10 3 m.
d. 4.5 x 10 6 m.
e. None of these are correct.
During a test of cornering ability, 0.67 g is reported as the maximum acceleration with which a vehicle can
negotiate a turn on level pavement. Assuming a turn with a radius of 100 m, the maximum speed for this vehicle
on the turn is:
a. 0.26 m/s.
b. 26. m/s.
c. 31. m/s.
d. 6.6 x 10 2 m/s.
e. None of these are correct.
During the design of a loop-the-loop on a roller coaster, the designer wants to have a car just barely touching
the track at the top of a loop when the car is traveling 12.0 m/s. Assuming the track exerts a negligible force on
the car at this point at the top of the loop, what should be the loop radius?
a. 3.83 m
b. 14.7 m
c. 118 m
d. 1.41 x 103 m
e. None of these are correct.
If a ball traveling at 500 m/s has a momentum whose magnitude is 70 kg m/s, its mass must be:
a. 0.14 kg
b. 7.1kg
c. 3.5 x 104 kg
d. Unable to be computed from these data.
e. None of these.
During a 45 to 65 mph passing test, a car's momentum changes by 1.3 x 104 kg m/s. If this occurs in 5.2 s, the
size of the average force acting on the car is:
a. 4.0 x 10-4 N
b. 2.5 x 103 N
c. 6.8 x 104 N
d. Unable to be computed from these data.
e. None of these.
____ 35. A 4.0 kg mass is sliding freely across a smooth, level surface such as a air-hockey table or an ice rink. It is
moving 5.0 m/s north. 6.0 s after this, it is moving 7.0 m/s north. What was its change in momentum during this
6.0 s interval?
a. Zero.
b. 1.3 kg m/s north.
c. 8.0 kg m/s north.
d. 28 kg m/s north.
e. None of these.
____ 36. During a "walk" in space, an astronaut is supposed to go to an outside section of the spacecraft and reorient a
stuck antenna. To move from the hatch along the side of the spacecraft forward to the site of the antenna the
astronaut will make the best progress:
a. by doing the "moonwalk".
b. using a motion more like swimming than walking.
c. taking a sack of empty food containers and throwing them forward one at a time.
d. taking a sack of empty food containers and throwing them backward one at a time.
e. leaning backward while stepping forward and then bending forward at the waist to get
over their feet again before taking the next step.
1.
2.
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35.
Answers (Don’t peek until you’ve tried each problem)
B
B
D
C
C
D
A
B
C
B
A
C
A
C
B
D
D
B
C
D
C
A
C
B
D
C
B
A
A
C
B
B
A
B
C
36.D