Work

In which of the following situations do your arms do work on books?

• holding a heavy stack of books while standing

• dropping a stack of books onto a table

• picking up a pile of books from the floor

• carrying a heavy stack of books

How much work is done lifting a 9.10-kg box straight up onto a shelf that is 1.80 m high? Find Force by F = Mass x Acceleration

• 5 J

• 160 J

• 16 J

• 50 J

Using the scientific definition, which statement is always true of work?

• It is difficult.

• It is done with a machine.

• It involves levers.

• It involves a transfer of energy.

The kinetic energy from an object’s motion always changes when which factor changes?

• the object's speed

• the object's volume

• the object's chemical potential energy

• the object's direction of motion

According to the graph, what is the kinetic energy at 2 s?

• 200 J

• 10 J

• 21 J

• 15 J

At which position(s) does the pendulum have maximum gravitational potential energy

• Position 1 and 5

• Position 1 and 3

• Position 5

• Position 1

At which position(s) does the pendulum have maximum kinetic energy

• Position 3

• Position 1

• Position 5

• Position 2 and 4

The kinetic energy of the golf club would be greatest at

• point A

• point B

• point C

• point D

Which energy transformation is happening in the photo?

• mechanical energy to chemical potential energy

• kinetic energy to elastic energy

• GPE to mechanical

• thermal energy to mechanical energy

Explain the role friction plays in the conservation of energy

• The total energy of a system when it has potential and kinetic energy does not remain constant. Energy escapes and gets added.

• The law of the conservation of energy states the energy can be created or destroyed.

• Friction causes some of the mechanical energy of an object to change into thermal energy. The total energy of a system—potential and kinetic plus any converted energy—remains constant.

• Friction causes thermal energy because energy is added to the system. The total energy of a system goes up and down and changes over time.