Available Answers

1. 1.

   Tick (√) the correct option:

   1. Which of the following will offer the least friction?
      1. Rough surface
      2. Smooth surface
      3. Highly polished surface
      4. All of these
   2. The decreasing order of friction is
      1. Rolling friction < Sliding friction < Limiting friction
      2. Rolling friction < Sliding friction < Limiting friction
      3. Rolling friction < Limiting friction < Sliding friction
      4. Limiting friction < Rolling friction < Sliding friction
   3. The method to reduce the friction is
      1. Polishing
      2. Streamlining
      3. Lubricating
      4. All of these
   4. Sliding friction is
      1. Less than rolling friction
      2. Equal to rolling friction
      3. Greater than rolling friction
      4. Can't say
   5. The method to increase the friction is
      1. Polishing
      2. Roughness
      3. Streamlining
      4. Lubrication
   6. The force which opposes the motion of a body over another is called
      1. Surface tension
      2. Gravitational force
      3. Force of friction
      4. Pressure
   7. The friction is due to the
      1. Roughness of the two surfaces in contact
      2. Roughness of the one surface only
      3. smoothness of surfaces
      4. None of these
2. 2.

   Fill in the blanks:

   1. Friction always opposes _____________ motion.
   2. Sliding friction is _____________ than rolling friction.
   3. Lubricants are used to _____________ friction.
   4. Boats and aeroplanes are _____________, so as to reduce fluid friction.
3. 3.

   Tick (√) the correct and cross (x) the wrong statement:

   1. Friction causes wastage of energy.
   2. Friction between two surfaces can be increased by polishing the surfaces.
   3. The friction between the brake shoe and rim of a bicycle is sliding friction.
4. 4.

   Find the odd one out:

   1. streamlining, ball bearing, lubrication, increasing roughness.
   2. wheels, ball-bearings, rolling friction, walking.
5. 5.

   What happens to the force of friction if the surfaces of contact are made smooth?
6. 6.

   What is the other name given to sliding friction?