Worksheet on types of friction and their effects on moving objects.

Problem Analysis and Solution:

Let's solve each question step by step.

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#### Question 1:
A moving ball on a ground stops after some time. Name the force responsible for it.

- When a ball is rolling on the ground, it eventually comes to a stop due to the presence of frictional forces.
- Friction opposes the motion of the ball and dissipates its kinetic energy as heat, causing it to slow down and eventually stop.

Answer: Friction

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#### Question 2:
Name the Type of friction in following two cases:

1. Case 1 (Pushing a heavy box):
- When you push a heavy box across the floor, the box slides over the surface. The resistance to this sliding motion is called sliding friction.
- Sliding friction occurs when two solid surfaces are in contact and one is moving relative to the other.

2. Case 2 (Pulling a suitcase with wheels):
- When you pull a suitcase with wheels, the wheels roll over the surface. The resistance to this rolling motion is called rolling friction.
- Rolling friction is generally much smaller than sliding friction because the contact between the wheel and the surface is minimal and involves less deformation.

Answers:
- Case 1: Sliding friction
- Case 2: Rolling friction

Out of the above two types of friction, name the friction which requires less effort:
- Rolling friction requires less effort compared to sliding friction because it involves less resistance.

Answer: Rolling friction

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#### Question 3:
Match the following:

| i) Bird | a) Measures the force acting on an object. |
| ii) Spring Balance | b) Static friction |
| iii) Moving body | c) Lubricant |
| iv) Reduces friction | d) Drag |

1. Bird: Birds experience air resistance when they fly, which is known as drag.
- Match: i) Bird → d) Drag

2. Spring Balance: A spring balance is used to measure the force acting on an object by observing the extension or compression of the spring.
- Match: ii) Spring Balance → a) Measures the force acting on an object.

3. Moving body: When a body is in motion, it experiences dynamic friction (or kinetic friction). However, if the body is stationary but has the potential to move, it experiences static friction.
- Match: iii) Moving body → b) Static friction

4. Reduces friction: Lubricants (such as oil or grease) are used to reduce friction by creating a thin layer between surfaces, minimizing direct contact.
- Match: iv) Reduces friction → c) Lubricant

Matches:
- i) Bird → d) Drag
- ii) Spring Balance → a) Measures the force acting on an object.
- iii) Moving body → b) Static friction
- iv) Reduces friction → c) Lubricant

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#### Question 4:
Choose the correct option:

i) Static friction comes to play when the object is:
- Static friction acts when an object is at rest but there is an external force trying to make it move. It prevents the object from starting to move.
- Options:
- a) Rolling
- b) Sliding
- c) Moves from rest
- d) None

Correct Answer: c) Moves from rest

ii) Rolling friction comes to play when the object is:
- Rolling friction occurs when an object rolls over a surface. It is much smaller than sliding friction and depends on the nature of the rolling surface and the material of the object.
- Options:
- a) Rolling
- b) Sliding
- c) Comes to rest
- d) All of these

Correct Answer: a) Rolling

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Final Answers:

1. Friction
2.
- Case 1: Sliding friction
- Case 2: Rolling friction
- Less effort: Rolling friction
3.
- i) Bird → d) Drag
- ii) Spring Balance → a) Measures the force acting on an object.
- iii) Moving body → b) Static friction
- iv) Reduces friction → c) Lubricant
4.
- i) c) Moves from rest
- ii) a) Rolling

Boxed Final Answer:
\[
\boxed{
\text{1. Friction} \\
\text{2. Sliding friction, Rolling friction, Rolling friction} \\
\text{3. i) d, ii) a, iii) b, iv) c} \\
\text{4. i) c, ii) a}
}
\]