whenever a force acts on the object.

whenever a force acts at 90^o to the displacement of the object.

whenever a force causes a displacement of the object.

whenever a net force acts on the object.

A weightlifter lifts a barbell.

A weightlifter holds a barbell overhead.

A weightlifter slowly lowers a barbell.

A weightlifter drops a barbell and the barbell falls to the ground.

the force is in the same direction as the displacement.

the force is acting at 90^o to the displacement.

the component of the force that does work is the direction opposite to the displacement.

the force acts in the opposite direction to the displacement.

The force of gravity does negative work when the worker lifts the bucket.

The painter does positive work on the bucket when carrying it horizontally at constant speed.

The painter does positive work on the bucket when setting it down.

No net work is done on the bucket.

 $W=Fd$  

 $W=Fd\cos\theta$  

 $W=Fd\sin\theta$  

 $W=mg\sin\theta$  

N.

N $\cdot$ m

N/m

kg $\cdot$ $\frac{m}{s^2}$

The force of gravity is the only force doing work on the parachutist.

Air resistance is the only force doing work on the parachutist.

No forces are doing work on the parachutist.

No net work is done on the parachutist.

kinetic energy.

potential energy.

gravitational potential energy.

elastic potential energy.

kinetic energy.

nonmechanical energy.

gravitational potential energy.

elastic potential energy.

The kinetic energy decreases to half its original value.

The kinetic energy doubles.

The kinetic energy increases by a factor of 4.

The kinetic energy does not change.

the net work done on an object equals the mechanical energy of the object.

the net work done on an object equals the change in mechanical energy of the object.

the change in the net work done on an object equals the mechanical energy of the object.

the change in the net work done on an object equals the change in the mechanical energy of the object.

an object´s mass

an object´s height relative to a zero level

the free-fall acceleration

the object´s speed

an object´s mass

an object´s height relative to a zero level

the free-fall acceleration

an object´s speed

Kinetic energy

Gravitational potential energy

Elastic potential energy

Geothermic energy

True

False

Is increased

Increases by 2

Increases by 1/2

Increases by 1/4

A lot

It is not possible to know

Zero joules

1/2m  $$v^2$$  

Not possible to be determined

1/2m $$v^2$$  

1000J

Zero joules

Final velolcity is zero and initial velocity is not zero

Friction is always directed at $$180\degree$$  from the displacement

It is not possible to know

That is the way it is