Class 8 Science

# Friction

## Extra Questions

#### Multiple Choice Questions

Question 1: Which of the following uses spikes in shoes?

• Lawyer
• Doctor
• Rugby player
• Painter

Answer: (c) Rugby player

Question 2: Mobil oil is used in scooters and bikes for which purpose?

• As fuel
• For reducing friction
• For increasing friction
• None of the above

Answer: (b) For reducing friction

Question 3: Tyres of which vehicles are biggest treads among the following?

• Race car
• Car
• Motorbike
• Excavator

Answer: (d) Excavator

Question 4: Which of the following is used in powdered form as lubricant?

• Graphite
• Chalk
• Salt
• Sugar

Answer: (a) Graphite

Question 5: Increasing friction is necessary for which of the following?

• Free wheel of bicycle
• Bicycle handle bar
• Chain of bicycle
• Ball bearing in front wheel

Answer: (b) Bicycle handle bar

Question 6: Which of the following surfaces will offer the least friction?

• Vinyl floor
• Plywood
• Plastic
• Ice

Answer: (d) Ice

Question 7: Least amount of friction is required in which of the following sports?

• Car Race
• Football
• Ice Skating
• Tug of war

Answer: (c) Ice Skating

### Very Short Answer Type Questions

Question 1: What is friction?

Answer: The force created due to relative movement between two surfaces is called friction.

Question 2: What is static friction?

Answer: The minimum amount of force that is required to overcome the force of friction is called static friction.

Question 3: What is sliding friction?

Answer: Once an object starts moving on a surface, some force is required to keep the object moving. The minimum force that is required to keep a moving object in motion at a constant speed is called sliding friction.

Question 4: What is rolling friction?

Answer: When an object rolls over a surface, the friction created is called rolling friction.

Question 5: Arrange different types of friction in descending order?

Answer: Static friction > Sliding friction > Rolling friction

Question 6: What is fluid friction?

Answer: Friction due to a fluid is called fluid friction or drag.

Question 7: What is a streamlined shape?

Answer: A shape which is wide in middle and tapered at ends is called a streamlined shape.