📝 Exercise on Force & Friction
📌 Objective Questions (Choose the correct answer)
1. Magnetic force is an example of:
- a. Action-at-a-distance force
- b. Non-contact force
- c. Contact force
- d. Both (a) and (b)
✅ Correct Answer: d. Both (a) and (b)
2. Which of these is contact force?
- a. Electrostatic force
- b. Muscular force
- c. Gravitational force
- d. Magnetic force
✅ Correct Answer: b. Muscular force
3. Which of the following methods is used to increase friction?
- a. Lubrication
- b. Polishing
- c. Increasing roughness
- d. Reducing roughness
✅ Correct Answer: c. Increasing roughness
4. Which of the following is used to decrease friction?
- a. Increasing roughness
- b. Streamlining
- c. Making grooves
- d. Using rubber grip
✅ Correct Answer: b. Streamlining
✍️ Fill in the blanks
1. Muscular force is an example of ______ force.
✅ Answer: Contact force
2. ______ exists between two surfaces when they rub against each other.
✅ Answer: Friction
3. The frictional force that acts between two surfaces when one of them rolls on top of the other is called ______ friction.
✅ Answer: Rolling friction
4. ______ is produced due to friction.
✅ Answer: Heat
5. Friction force is a ______ force.
✅ Answer: Contact force
✔️ True or False
1. Rolling friction is more than sliding friction.
❌ False (Rolling friction is less than sliding friction)
2. Handles of cricket bats and bicycles are covered with rubber grips to increase friction.
✅ True
3. Force can change the mass of an object.
❌ False (Force changes motion, not mass)
4. The magnitude of static friction varies between zero and the smallest force needed to start motion.
✅ True
5. Friction is a necessary evil.
✅ True
🔗 Match the following
Match the following pairs:
1. Static friction 2. Sliding friction 3. Rolling friction 4. Lubricants 5. Grooves on tyres
✅ Answers:
1 → e. No motion
2 → c. Sliding motion
3 → d. Rolling motion
4 → b. Reduces friction
5 → a. Increases friction
