ICAS Physical Sciences (Forces, Energy, Light and Sound)

Question 1

Which force pulls objects toward the centre of the Earth?

Accepted Answer

Gravity

Answer

Gravity is the force of attraction between masses. Earth's gravity pulls objects toward its centre, which is why dropped things fall.

Question 2

Which material is the best conductor of electricity?

Accepted Answer

Copper

Answer

Copper is a metal with free-moving electrons, so electricity flows through it easily. Rubber, plastic and wood are insulators.

Question 3

Through which of these does sound travel fastest?

Accepted Answer

Steel

Answer

Sound travels fastest through solids such as steel because the particles are packed closely together. It cannot travel through a vacuum at all.

Question 4

A ball rolls across smooth tiles, then onto carpet, where it slows down quickly. Which force mainly slows it on the carpet?

Accepted Answer

Friction

Answer

Friction is the force between two surfaces rubbing together. Rough carpet creates more friction than smooth tiles, so the ball slows faster.

Question 5

Why does a shadow form behind an object placed in a beam of light?

Accepted Answer

Light travels in straight lines and cannot pass through the object

Answer

Light travels in straight lines. An opaque object blocks the light, leaving an area behind it that the light cannot reach. That area is the shadow.

(ICAS) ICAS Practice Test