Download Work and Kinetic Energy

Q1) Which of the following statements is true?
1) Joe will probably get hit and need plastic surgery.
2) Joe is safe because there is air resistance.
3) Joe would be safe even if we ignored air resistance.
Q2) No work is done by gravity on a bowling ball that
rolls along a bowling alley because
1) no force acts on the ball
2) no distance is covered by the ball
3) the force on the ball is perpendicular to the ball’s
motion
4) all of the above
5) none of the above
Q3) Which requires more work: lifting a 50 kg sack
vertically 2 meters or lifting a 25 kg sack vertically
4 meters?
1) lifting the 50 kg sack
2) lifting the 25 kg sack
3) both require the same amount of work
Q4) The figure shows four situations in which a force acts on a box
while the box slides rightward a distance d across a frictionless
floor. The magnitudes of the forces are identical; their orientations
are as shown. Rank the situations according to the work done on
the box during the displacement, from most positive to most
negative.
1) d, c, b, a
2) a, b, c, d
3) a, c, d, b
4) c, d, b, a
5) none of the above
Q5) Can the normal force ever do nonzero work on
an object?
1) yes
2) no
Q6) A rock of mass m is twirled on a string in a horizontal plane.
The work done by the tension in the string on the rock is
1) +
2) 
3) 0
Q7) When a person walks, the force of friction between the
floor and the person's feet accelerates the person forward.
The floor does
1) Positive work on the person.
2) Negative work on the person.
3) No work on the person.
Q7) An object moves in a circle at constant speed. The work
done by the centripetal force is zero because:
1) the displacement for each revolution is zero
2) the average force for each revolution is zero
3) there is no friction
4) the magnitude of the acceleration is zero
5) none of the above
Q8) A line drive to the shortstop is caught at the same height as it
was originally hit. Over its entire flight the work done by gravity
and the work done by air resistance, respectively, are:
1) zero; positive
2) zero; negative
3) positive; negative
4) negative; positive
5) negative; negative
Q9) A particle moves 5m in the positive x direction while being
acted upon by a constant force F = (4N)i + (2N)j - (4 N)k. The
work done on the particle by this force is:
1) 20 J
2) 10 J
3) -20 J
4) 30 J
5) is impossible to calculate without knowing other forces
Q10) Which one of the following statements concerning kinetic
energy is true?
1) It can be measured in watts.
2) It is always equal to the potential energy.
3) It is always positive.
4) It is a quantitative measure of inertia.
5) It is directly proportional to velocity.
Q11) If a bowling ball and a golf ball both move with
the same kinetic energy, can you say which has the
greater speed?
1) no, you can not say which has the greater speed
2) yes, the golf ball has the greater speed
3) yes, the bowling ball has the greater speed
Q12) How much kinetic energy does a car have when it
moves at 100 km/hr, as compared with when it moves
at 50 km/hr?
1) the same amount of KE
2) 2 times as much KE
3) 4 times as much KE
4) 16 times as much KE
Q13) A particle moves along an x axis. Does the kinetic
energy of the particle increase, decrease, or remain the same
if the particle's velocity changes (a) from -3 m/s to -2 m/s
and (b) from -2 m/s to 2 m/s?
1) (a) increase
2) (a) increase
3) (a) decrease
4) (a) decrease
(b) increase
(b) stay the same
(b) decrease
(b) stay the same
Q14) Compared to the amount of work required to accelerate
a car from rest to 10 m/s, the amount of energy required to
accelerate the same car from 10 m/s to 20 m/s is
1) the same
2) twice as much
3) three times as much
4) four times as much
Q15) Suppose you want to ride your mountain bike up a steep hill.
Two paths lead from the base to the top, one twice as long as the
other. Compared to the average force you would exert if you took
the short path, the average force you exert along the longer path is
1) four times as small.
2) three times as small.
3) half as small.
4) the same.
5) undetermined—it depends on the time taken.
Q16) In raising an object to a given height by means of an inclined
plane, as compared with raising the object vertically, there is a
reduction in:
1) work required
2) distance pushed
3) friction
4) force required
5) value of the acceleration due to gravity
Q17) A 4-kg cart starts up an incline with a speed of 3 m/s
and comes to rest 2 m up the incline. The total work done on
the car is:
1) 6 J
2) 8 J
3) 12 J
4) 18 J
5) none of the above
Q18) A 5.0 kg particle has 160 J of work done on it. If its initial
speed is zero, what is its final speed in m/s?
1)
2)
3)
4)
5)
5.0
6.0
7.0
8.0
9.0
Q19) A block is attached to the end of an ideal spring and
moved from coordinate xi to coordinate xf . The relaxed
position is at x = 0. The work done by spring is positive if:
1) xi = 2cm and xf = 4cm
2) xi = -2 cm and xf = 4cm
3) xi = -2 cm and xf = -4 cm
4) xi = 2 cm and xf = -4 cm
5) xi = -4 cm and xf = -2 cm
Q20) A hockey puck sliding on an ice rink is moving at 1 m/s
when it slides onto a carpet that someone left on the ice. The puck
comes to rest after moving 1m on the carpet. How far along the
carpet would the puck go, if its initial speed was 2 m/s?
1) 1.5m
2) 2m
5) Impossible to determine.
3) 3m
4) 4m
Q21) A cart on an air track is moving at 0.5 m/s when the air is
suddenly turned off. The cart comes to rest after traveling 1 m. The
experiment is repeated, but now the cart is moving at 1 m/s when
the air is turned off. How far does the cart travel before coming to
rest?
1) 1 m
2) 2 m
5) not enough information
3) 4 m
4) 1/2 m
Q22) A puck moving across a horizontal surface experiences
constant negative acceleration due to friction, and comes to rest
after 12 seconds. How does the energy lost in the first 6 seconds
compare to the energy lost in the last 6 seconds?
1) first half > second half
2) first half = second half
3) first half < second half
4) too little information
Q23) Power has the dimensions of:
1) ML2/T2
2) MT/L2
3) ML/T2
4) ML2/T3
5) none of these
Q24) What power is needed to lift a 49 kg person at a
constant velocity a vertical distance of 5.0 m in 20.0 s?
1) 12.5 W
4) 120 W
2) 25 W
5) 210 W
3) 60 W