Transcript C05 Energy (Concept)

Chapter 5
Energy
Phy 2053
Conceptual
Questions
Phy 2053 Conceptual Questions
Concept Questions 05-01/14
If you push twice as hard against a stationary brick wall,
the amount of work you do
A) doubles.
B) remains constant at zero.
C) remains constant but non-zero.
D) is cut in half.
Phy 2053 Conceptual Questions
Concept Questions 05-02/14
If you walk 5.0 m horizontally forward at a constant
velocity carrying a 10 N object, the amount of work
you do is
A) more than 50 J.
B) zero.
C) less than 50 J, but more than 0 J.
D) equal to 50 J.
Phy 2053 Conceptual Questions
Concept Questions 05-03/14
You throw a ball straight up. Compare the sign of the work
done by gravity while the ball goes up with the sign of the
work done by gravity while it goes down.
A) Work is + on the way up and + on the way down.
B) Work is + on the way up and - on the way down.
C) Work is - on the way up and + on the way down.
D) Work is - on the way up and - on the way down.
Phy 2053 Conceptual Questions
Concept Questions 05-04/14
A truck weighs twice as much as a car, and is moving at
twice the speed of the car. Which statement is true
about the truck's kinetic energy compared to that of the
car?
A) All that can be said is that the truck has more kinetic energy.
B) The truck has twice the kinetic energy of the car.
C) The truck has 4 times the kinetic energy of the car.
D) The truck has 8 times the kinetic energy of the car.
Phy 2053 Conceptual Questions
Concept Questions 05-05/14
An object hits a wall and bounces back with half of its
original speed. What is the ratio of the final kinetic
energy to the initial kinetic energy?
A) 1/2
B) 1/4
C) 2
D) 4
Phy 2053 Conceptual Questions
Concept Questions 05-06/14
You slam on the brakes of your car in a panic, and skid a
certain distance on a straight, level road. If you had been
traveling twice as fast, what distance would the car have
skidded, under the same conditions?
A) It would have skidded 4 times farther.
B) It would have skidded twice as far.
C) It would have skidded 1.4 times farther.
D) It is impossible to tell from the information given.
Phy 2053 Conceptual Questions
Concept Questions 05-07/14
Is it possible for a system to have negative potential energy?
A) Yes, as long as the total energy is positive.
B) Yes, since the choice of the zero of potential energy
is arbitrary.
C) No, because the kinetic energy of a system must equal
its potential energy.
D) No, because this would have no physical meaning.
Phy 2053 Conceptual Questions
Concept Questions 05-08/14
An object is released from rest a height h above the ground.
A second object with four times the mass of the first if
released from the same height. The initial potential energy
of the second object compared to the first is
A) one-fourth as much.
B) one-half as much.
C) twice as much.
D) four times as much.
Phy 2053 Conceptual Questions
Concept Questions 05-09/14
The total mechanical energy of a system
A) is equally divided between kinetic energy and
potential energy.
B) is either all kinetic energy or all potential energy,
at any one instant.
C) can never be negative.
D) is constant, only if conservative forces act.
Phy 2053 Conceptual Questions
Concept Questions 05-10/14
A lightweight object and a very heavy object are sliding with
equal speeds along a level frictionless surface. They both
slide up the same frictionless hill.
Which rises to a greater height?
A) The heavy object, because it has greater kinetic energy.
B) They both slide to the same height.
C) The lightweight object, because it weighs less.
D) Cannot be determined from the information given.
Phy 2053 Conceptual Questions
Concept Questions 05-11/14
Fd
The quantity
is
t
A) the kinetic energy of the object.
B) the potential energy of the object.
C) the work done on the object by the force.
D) the power supplied to the object by the force.
Phy 2053 Conceptual Questions
Concept Questions 05-12/14
What is the correct unit of power expressed in SI units?
A) kg m/s2
B) kg m2/s2
C) kg m2/s3
D) kg2 m/s2
Phy 2053 Conceptual Questions
Concept Questions 05-13/14
Compared to yesterday, you did 3 times the work in one-third
the time. To do so, your power output must have been
A) the same as yesterday's power output.
B) one-third of yesterday's power output.
C) 3 times yesterday's power output.
D) 9 times yesterday's power output.
Phy 2053 Conceptual Questions
Concept Questions 05-14/14
Of the following, which is not a unit of power?
A) watt/second
B) newton-meter/second
C) joule/second
D) watt
Phy 2053 Conceptual Questions