Case Study, Force and Pressure

ICSE Class 8 Physics
Case Study Based Questions

Case Study: Steering Wheel and Moment of Force

During a school trip, Samay watched the bus driver. The bus had a large steering wheel. The driver always held the steering wheel near the outer edge while turning. Samay tried holding the wheel close to the centre and found it difficult to turn. He also noticed that whenever the driver pushed the wheel at an angle, turning became harder.

1. Why was Samay not able to turn the steering wheel easily when he held it close to the centre?

When Samay held the steering wheel near the centre, the perpendicular distance from the axis of rotation became very small. Since moment of force depends on distance from the pivot, a smaller distance produced a smaller turning effect. Therefore, turning the wheel became difficult.

2. Why does holding the steering wheel at the outer edge make turning easier?

At the outer edge, the distance from the centre of rotation is maximum. A larger distance produces a greater moment of force. Therefore, less effort is needed to turn the steering wheel.

3. Why does turning become harder when the force is applied at an angle?

The maximum turning effect is produced when force acts perpendicular to the steering wheel. When force is applied at an angle, only a part of the force contributes to rotation. Hence the moment of force decreases and turning becomes harder.

4. Why do buses have larger steering wheels than cars?

Buses are heavier vehicles and require a larger turning effect. A larger steering wheel provides a greater radius, which increases the moment of force. Therefore, the driver can turn the bus more easily.

5. Which formula explains the working of a steering wheel?

Moment of Force = Force × Perpendicular Distance M = F × d

6. Name two factors on which moment of force depends.

1. Magnitude of the force applied.
2. Perpendicular distance of the force from the axis of rotation.