Energy Change

When a handphone charger is used, what is the energy change?

__________ energy to __________ energy

• chemical potential energy to electrical energy

• electrical energy to kinetic energy

• electrical energy to sound energy

• electrical energy to chemical potential energy

The unit for Power is _______.

• Joule

• Newton

• Watt

• Metre

The unit for Energy is __________.

• Newton

• Newton

• Kilogram

• Joule

Energy can be destroyed. True or False?

• True

• False

A fan uses 800 J of electrical energy. 123 J of sound energy is produced, and 456 J of kinetic energy is produced. The rest is heat energy. How much heat energy is given off?

• 221J

• 344J

• 579J

• 677J

Which of the following objects has kinetic energy?

• a moving car

• a loaf of bread

• a stretched spring

• water stored in rooftop tank

When a metal spoon is put into a hot cup of coffee, thermal energy is ________.

• produced by spoon

• produced by the coffee in the cup

• transferred from the coffee to the spoon

• transferred from the spoon to the coffee

Which of the following is the most suitable source of renewable energy for Singapore?

• wind

• solar

• biomass

• hydroelectric

If the useful power output of a wind generator is 25 000W, calculate the electrical energy produced every minute.

• 60J

• 417J

• 25 000J

• 1500 000J

The amount of energy needed for John to climb a tree is 1200J. If he can complete the climb in 20s, calculate the power.

• 20W

• 60W

• 1200W

• 24 000W