3A1 Energy and Its Uses

Energy can be created and destroyed.

• True

• False

Answer explanation

Principle of Conservation of Energy states that energy CANNOT be created nor destroyed! It can only be changed from one type to another.

(e.g. A basket ball is thrown upwards: Kinetic energy (it is very fast when it is first thrown) is converted to gravitational potential energy (it increases is height above ground).

Which of the following is a type of energy?

• Light energy

• Thermal energy

• Sound energy

• Kinetic energy

Answer explanation

All of the above is correct!

Which of the following is a type of energy?

• Gravitational potential energy

• Chemical energy

• Elastic potential energy

• Food energy

Answer explanation

The correct answers are:

- Gravitational potential energy

- Elastic potential energy

The following is wrong:

- Chemical energy: SHOULD be Chemical POTENTIAL energy

- Food energy: No such thing. In food, it contains chemical potential energy.

An object with a smaller mass has more kinetic energy.

• True

• False

Answer explanation

The statement is FALSE!

An object with a smaller mass has a smaller kinetic energy.

Similarly,

an object with a greater mass has a greater kinetic energy.

An object with a greater speed has a greater kinetic energy.

• True

• False

Answer explanation

The statement is TRUE!

An object with a greater speed (meaning it is moving faster), has a greater kinetic energy.

Similarly,

an object with a smaller speed (moving slower), has a smaller kinetic energy.

An object higher above ground has higher gravitational potential energy.

• True

• False

Answer explanation

The statement is true!

The higher the object above ground, the more gravitational potential energy it has!

Similarly,

the closer the object to the ground, the lower gravitational potential energy it has.

A battery-powered torch light is switched on.

_____________ energy is converted into light energy.

An electrical fan is switched on.

Electrical energy -> _________ energy in the turbine of the fan

Jayden throws a basketball vertically upwards.

Kinetic energy -> __________ energy

Thermal energy moves from lower temperature to higher temperature.

• True

• False

Answer explanation

The statement is false!

Thermal energy always moves from higher temperature to lower temperature.

E.g. Your cup of hot milo will cool down when placed in a refrigerator because thermal energy is lost by the hot milo to the cold air in the refrigerator.