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Question 1:

Which of the following is an example of a positive effect of friction?

A) Wearing out of tires
B) Slowing down of a moving car
C) Formation of blisters on the skin
D) Heating up of mechanical parts

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Explanation: The correct answer is B) Slowing down of a moving car. The positive effect of friction in this case is that it allows the car's brakes to slow down and stop the car by converting kinetic energy into heat energy. Without friction, it would be challenging to control the speed and motion of vehicles.

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Question 2:

Which of the following is an example of a negative effect of friction?

A) Enhancing traction for walking
B) Wearing down of mechanical parts
C) Generating heat in a car engine
D) Stopping a sliding object

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Explanation: The correct answer is B) Wearing down of mechanical parts. The negative effect of friction in this case is that it causes the surfaces of mechanical parts to experience wear and tear over time. This can lead to decreased efficiency, increased maintenance needs, and potential damage or failure of the parts.

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Question 3:

Which of the following is an application of friction in everyday life?

A) Lubricating mechanical parts
B) Reducing air resistance during skydiving
C) Enhancing grip while walking
D) Reducing wear on tires

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Explanation: The correct answer is C) Enhancing grip while walking. Friction between the shoes and the ground allows for better traction, which enhances grip and stability while walking. Without friction, it would be difficult to maintain balance and walk smoothly.

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Question 4:

Which of the following is an example of a dynamic effect of friction?

A) Slowing down of a moving bicycle
B) Formation of ice on roads
C) Ball bearings reducing friction
D) Static friction preventing

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Explanation: The correct answer is A) Slowing down of a moving bicycle. The dynamic effect of friction in this case is that it acts opposite to the direction of motion of the bicycle, causing it to slow down. This effect is particularly noticeable when applying the brakes, as the friction between the brake pads and the wheel rim or disc helps to reduce the bicycle's speed.

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Question 5:

Which of the following factors does not affect the magnitude of friction?

A) The nature of the surfaces in contact
B) The normal force between the surfaces
C) The area of contact between the surfaces
D) The weight of the object

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Explanation: The correct answer is D) The weight of the object. The magnitude of friction depends on the nature of the surfaces in contact (e.g., roughness, texture), the normal force (perpendicular force) between the surfaces, and the area of contact between the surfaces. However, the weight of the object, which is the force due to gravity acting on it, does not directly affect the magnitude of friction.