Revision 2
First Term.
Question 3
1. Draw a neat and labelled diagram demonstrating the motion of a simple pendulum.
Diagram should show: rigid support, string (effective length L), bob at mean position, extreme positions (amplitude A), and arrows showing oscillation.
2. Define the effective length, amplitude, and frequency of oscillation.
Effective Length: Distance between point of suspension and centre of the bob.
Amplitude: Maximum displacement of bob from the mean position.
Frequency: Number of oscillations completed per second.
3. Differentiate between mass and weight.
| Mass | Weight |
|---|---|
| Amount of matter in a body | Force with which Earth attracts a body |
| Constant everywhere | Varies with gravity (g) |
| Scalar, SI unit: kilogram (kg) | Vector, SI unit: newton (N) |
4. State three sources of sound energy.
1. Vibrating vocal cords
2. Vibrating tuning fork
3. Musical instruments (e.g., guitar, flute, drums)
Question 4
1. State the energy changes in the following:
Battery: Chemical → Electrical
Bulb: Electrical → Light + Heat. Guitar - mechanical to sound, Photosynthesis - light to chemical, Nuclear reactor - nuclear to electrical
2. State the type of motion displayed by each object:
Simple pendulum: Oscillatory motion
Earth around its own axis : Rotational motion
Bird: random
Swing: oscillatory (Periodic motion)
Question 5
1. A car travels 100 km in 3 hours and the next 100 km in 2 hours. Calculate the average speed.
Total distance = 200 km
Total time = 5 h
Average speed = 200 ÷ 5 = 40 km/h
2. A bus of mass 300 kg is moving at a speed of 40 km/h. Find its kinetic energy.
Convert speed: 40 km/h = 11.1 m/s
KE = ½ mv² = ½ × 300 × (11.1)² ≈ 18500 J
3. Why is energy conservation and prevention of wastage important?
- Energy resources are limited
- Ensures availability for future generations
- Reduces pollution and cost
4. Calculate the time period of a simple pendulum if the oscillation frequency is 0.5 Hz.
T = 1/f = 1/0.5 = 2 seconds
