O-Level Combined Science — Physics 1

Question 1

What is the SI unit of force?

Accepted Answer

Newton

Answer

The SI unit of force is the Newton (N), named after Sir Isaac Newton.

Question 2

A 5 kg object accelerates at 3 m/s². What is the net force acting on it?

Accepted Answer

15 N

Answer

F = ma = 5 × 3 = 15 N, using Newton's Second Law.

Question 3

Which type of wave requires a medium to travel?

Accepted Answer

Sound waves

Answer

Sound waves are mechanical waves that require a medium (solid, liquid, or gas) to travel; they cannot travel through a vacuum.

Question 4

What is the formula for density?

Accepted Answer

Density = Mass/Volume

Answer

Density = Mass/Volume (ρ = m/V), measured in kg/m³ or g/cm³.

Question 5

Which phenomenon explains why a straw appears bent when placed in a glass of water?

Accepted Answer

Refraction

Answer

Refraction is the bending of light as it passes from one medium (water) to another (air) at different speeds, making the straw appear bent.

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