8. Ball bearings are used to
a. give a streamlined shape
b. increase grip
c. increase drag
d. reduce friction
Write T for True and F for False statements. Correct the false statement/s.
1. Frictional force between two surfaces depends on the nature of the two surfaces.
2. Rolling friction is greater than sliding friction.
3. Ball bearings are used to increase friction.
4. Fluid friction acts between two moving solid surfaces in contact with each other.
5. Tyres of vehicles have treads to reduce speed.
Short answer type questions
Answer the following.
1. Give an example of contact force.
2. What is the SI unit of force?
3. What is a spring balance used for?
4. Give an example of non-contact force.
5. Give two advantages of friction.
Answer (2)
Ball bearings are used to: Answer choice (d) reduce friction.
Correct the True/False statements:
Frictional force between two surfaces depends on the nature of the two surfaces.
True. Different surfaces, like rough or smooth, create different levels of frictional forces when they are in contact.
Rolling friction is greater than sliding friction.
False. Rolling friction is usually less than sliding friction. This is why wheels and ball bearings are used—to make movement easier by reducing friction.
Ball bearings are used to increase friction.
False. Ball bearings are used to reduce friction between moving parts.
Fluid friction acts between two moving solid surfaces in contact with each other.
False. Fluid friction occurs when a solid object moves through a fluid, such as water or air, causing drag.
Tyres of vehicles have treads to reduce speed.
False. The treads on tires are designed to increase grip and provide better traction, especially in wet conditions, not primarily to reduce speed.
Short answer type questions:
Give an example of contact force.
Friction is an example of a contact force as it requires two surfaces to be in contact.
What is the SI unit of force?
The SI unit of force is the Newton (N).
What is a spring balance used for?
A spring balance is used to measure the force or weight of an object.
Give an example of non-contact force.
Gravity is an example of a non-contact force because it acts on objects without physical contact.
Give two advantages of friction.
Friction allows us to walk without slipping.
Friction between the tires and the road helps vehicles to slow down and stop effectively.
These answers provide basic explanations to help understand the concepts related to forces and friction in Physics.
Ball bearings are used to reduce friction between moving parts, not increase it. Friction depends on the nature of surfaces in contact and is crucial for activities like walking. Advantages of friction include providing grip to prevent slipping and allowing vehicles to stop safely.
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