Physics: Energy

Energy ______ be created or destroyed. It can only be ___________ between energy stores.

Energy can be transferred via...

• current

• waves

• heat

• forces

Answer explanation

Heat (thermal) is an energy store, not a method energy can be transferred by.

Which energy store.. depends on heat

• thermal

• kinetic

• nuclear

• electromagnetic

Which energy store.. depends on movement

• gravitational potential

• kinetic

• nuclear

• elastic

Which energy store.. depends on height

• thermal

• chemical

• gravitational potential

• electromagnetic

Which energy store.. changes be deforming a material/spring

• thermal

• kinetic

• elastic

• electromagnetic

What is the energy transfer if... a bus slows down

• kinetic --> thermal + sound (via force)

• kinetic + thermal --> sound (via current)

• kinetic --> thermal (via current)

• kinetic --> sound (via force)

Answer explanation

The bus was moving, meaning it already had kinetic energy. That kinetic energy, when being slowed down will transfer into thermal due to friction (the force). Sound can also be heard when a bus brakes, meaning some transferred to sound.

What is the energy transfer if... a person talks

• kinetic --> thermal (via force)

• kinetic --> thermal + sound (via force)

• sound --> kinetic + thermal (via waves)

• kinetic --> thermal + sound (via waves)

Answer explanation

The larynx (voice box) vibrates as someone talks, meaning there is some kinetic energy. This will transfer into thermal (as our breath is hot) and sound because sound is always heard when someone talks. Sound also travels as a longitudinal wave.

What is the energy transfer if... a fan is switch on

• chemical --> kinetic (via waves)

• chemical --> kinetic + sound (via currents)

• nuclear --> kinetic (via currents)

• chemical --> thermal + kinetic (via currents)

Answer explanation

Chemical energy in this case must come from an electric current. The fan will begin to move, meaning some has been transferred into kinetic energy. There can also be a slight noise heard when a fan is on, so that means some is sound energy.

What is the formula for kinetic energy?

Answer explanation

m = mass (kg)

v = velocity/speed (m/s)