Question 

(a) Fig. 3.1 shows a worker changing a lamp on a lamp post.

(i) The worker is lifted up to the top of the lamp post.

State the type of energy that has been gained by the worker when he has reached the top of the lamp post.

▶️Answer/Explanation

Gravitational potential energy.

(ii) As the worker changes the lamp, he drops his screwdriver.

State the type of energy that is gained by the screwdriver as it is falling to the ground.

▶️Answer/Explanation

Kinetic energy.

(iii) The worker applies a horizontal force of 10 N to the top of the lamp post.

The total height of the post is 10 m.

Calculate the moment of the force at the base of the post and state its units.

▶️Answer/Explanation

Moment = Force × Distance = 10 N × 10 m = 100 Nm.

Units: Nm (Newton meters).

(b) The worker switches on the lamp. The lamp emits visible light.

(i) Fig. 3.2 shows an incomplete electromagnetic spectrum.

On Fig. 3.2 write visible light in its correct position.

▶️Answer/Explanation

Visible light should be placed between ultraviolet and infrared on the electromagnetic spectrum.

(ii) Draw a line from each type of electromagnetic radiation to its use. One of the lines has been drawn for you.

▶️Answer/Explanation

Infrared → Heat sensing camera

Microwaves → Television signal transmission

Radio waves → Telephone transmission

X-rays → Airport security bag checking

(iii) Four types of electromagnetic radiation are listed in (b)(ii).

State which of these has the lowest frequency.

▶️Answer/Explanation

Radio waves.

(c) The worker drives a van for 15 minutes and travels 8 km.

Calculate the average speed of the van in m/s.

▶️Answer/Explanation

First, convert 15 minutes to seconds: 15 minutes × 60 seconds/minute = 900 seconds.

Convert 8 km to meters: 8 km × 1000 m/km = 8000 meters.

Average speed = Distance / Time = 8000 m / 900 s ≈ 8.89 m/s.