Question 1

A particle starts from rest and is acted on by a net force that does work at a rate that is proportional to the time t. The speed of the particle is proportional to:

Accepted Answer

A)    
B)  t 
C)  t2 
D)    
E)  1/t 
A)    
B)  t 
C)  t2 
D)    
E)  1/t

Question 2

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:

Accepted Answer

A)  xi = 2 cm and xf = 4 cm 
B)  xi = -2 cm and xf = 4 cm 
C)  xi = -2 cm and xf = -4 cm 
D)  xi = 2 cm and xf = -4 cm 
E)  xi = -4 cm and xf = -2 cm 
A)  xi = 2 cm and xf = 4 cm 
B)  xi = -2 cm and xf = 4 cm 
C)  xi = -2 cm and xf = -4 cm 
D)  xi = 2 cm and xf = -4 cm 
E)  xi = -4 cm and xf = -2 cm

Question 3

A woman lifts a barbell 2.0 m in 5.0 s. If she lifts it the same distance in 10 s, the work done by her is:

Accepted Answer

A)  four times as great 
B)  two times as great 
C)  the same 
D)  half as great 
E)  one-fourth as great 
A)  four times as great 
B)  two times as great 
C)  the same 
D)  half as great 
E)  one-fourth as great

Question 4

An escalator is used to move 20 people (60 kg each) per minute from the first floor of a department store to the second floor, 5 m above. The power required is approximately:

Accepted Answer

A)  100 W 
B)  200 W 
C)  1000 W 
D)  2000 W 
E)  60,000 W 
A)  100 W 
B)  200 W 
C)  1000 W 
D)  2000 W 
E)  60,000 W

Question 5

A man moves the 10-g object shown in a vertical plane from position X to position Y along a circular track of radius 20 m. The process takes 0.75 min. The work done by the man is about:

Accepted Answer

A)  1 J 
B)  2 J 
C)  4 J 
D)  6 J 
E)  12 J 
A)  1 J 
B)  2 J 
C)  4 J 
D)  6 J 
E)  12 J

Question 6

A 1-kg block is lifted vertically 1 m at constant speed by a boy. The work done by the boy is about:

Accepted Answer

A)  1 ft .lb 
B)  1 J 
C)  10 J 
D)  0.1 J 
E)  zero 
A)  1 ft .lb 
B)  1 J 
C)  10 J 
D)  0.1 J 
E)  zero

Question 7

An ideal spring, with a pointer attached to its end, hangs next to a scale. With a 100-N weight attached, the pointer indicates "40" on the scale as shown. Using a 200-N weight instead results in "60" on the scale. Using an unknown weight X instead results in "30" on the scale. The weight of X is:

Accepted Answer

A)  10 N 
B)  20 N 
C)  30 N 
D)  40 N 
E)  50 N 
A)  10 N 
B)  20 N 
C)  30 N 
D)  40 N 
E)  50 N

Exam 7: Kinetic Energy and Work

A particle starts from rest and is acted on by a net force that does work at a rate that is proportional to the time t. The speed of the particle is proportional to:

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:

A woman lifts a barbell 2.0 m in 5.0 s. If she lifts it the same distance in 10 s, the work done by her is:

An escalator is used to move 20 people (60 kg each) per minute from the first floor of a department store to the second floor, 5 m above. The power required is approximately:

A man moves the 10-g object shown in a vertical plane from position X to position Y along a circular track of radius 20 m. The process takes 0.75 min. The work done by the man is about:

A 1-kg block is lifted vertically 1 m at constant speed by a boy. The work done by the boy is about:

An ideal spring, with a pointer attached to its end, hangs next to a scale. With a 100-N weight attached, the pointer indicates "40" on the scale as shown. Using a 200-N weight instead results in "60" on the scale. Using an unknown weight X instead results in "30" on the scale. The weight of X is:

Measurement

Motion Along a Straight Line

Vector

Motion in Two and Three Dimensions

Force and Motion I

Force and Motion II

Potential Energy and Conservation of Energy

Center of Mass and Linear Momentum

Rotation

Rolling, Torque, and Angular Momentum

Equilibrium and Elasticity

Gravitation

Fluids

Oscillations

Waves I

Waves II

Temperature, Heat, and the First Law of Thermodynamics

The Kinetic Theory of Gases

Entropy and the Second Law of Thermodynamics

Electric Charge

Electric Fields

Gauss Law

Electric Potential

Capacitance

Current and Resistance

Circuits

Magnetic Fields

Magnetic Fields Due to Currents

Induction and Inductance

Electromagnetic Oscillations and Alternating Current

Maxwells Equations; Magnetism of Matter

Electromagnetic Waves

Images

Interference

Diffraction

Relativity

Photons and Matter Waves

More About Matter Waves

All About Atoms

Conduction of Electricity in Solids

Nuclear Physics

Energy From the Nucleus

Quarks, Leptons, and the Big Bang

Filters

A block is attached to the end of an ideal spring and moved from coordinate x_i to coordinate x_f. The relaxed position is at x = 0. The work done by spring is positive if: