Questions
In which direction does force of friction act?
- Upward direction
- Downward direction
- The direction opposite to motion
- The direction of motion
Why it is advised to apply machine oil or grease in the moving parts of a machine at regular intervals?
- To increase wearing by increasing friction
- To give it a shiny appearance
- To prevent wearing by decreasing friction
- To prevent wearing by increasing friction
It is difficult to drag a bucket full of water than an empty bucket because
- force of friction decreases as we drag a bucket full of water
- force of friction increases with the increase of normal force due to increased weight
- force of friction increases with the decrease of normal force due to increased weight
- force of friction is independent of the weight of the body
Why is the shape of an aeroplane designed in a manner similar to the shape of a bird?
- To increase fluid friction
- To reduce fluid friction
- To maintain fluid friction
- To eliminate friction completely
Friction cannot be increased by
- providing better contact
- decreasing roughness
- increasing normal force
- both (1) and (2)
If your cycle is cleaned and oiled regularly, it will run smoothly and will last longer. Why?
- It increases friction in moving parts of the cycle.
- It reduces friction in moving parts of the cycle.
- It increases heating in the parts of the cycle.
- Both (1) and (3)
Even a child can pull a piece of luggage fitted with rollers as compared to the one without rollers. Why?
- Because rolling friction is greater than the sliding friction
- Because rolling friction is smaller than the sliding friction
- Because rolling friction is equal to the sliding friction
- Because rolling friction and sliding friction oppose each other
Why do we slip, when we accidently step on a banana peel?
- Because of increased friction
- Because of reduced friction
- Because of reduced gravitational force
- Because of upward reaction
Which of the following statements is NOT true?
- Without friction a building could be easily constructed.
- Writing with pen or pencil could not be possible, if there was no friction.
- Friction depends on the nature of surfaces in contact.
- Friction is sometimes undesirable.
If oils or other liquid lubricants cannot be used to reduce friction in a machine, then which of the following statements is TRUE?
- An air cushion between the moving parts is used to reduce friction.
- Gun powder is sprinkled between the moving parts of a machine.
- The moving parts of the machines are made rough.
- Both (1) and (3).
Why are pavements and playing areas such as basketball courts made slightly rough?
- To reduce friction
- To increase friction
- To make it look different
- Both (1) and (3)
Which of the following statements is false?
- Friction can slow things down.
- Friction is never useful.
- Friction depends on the nature of surfaces in contact.
- Friction can stop things from moving.
Why is friction reduced on polishing the surface of a wooden table?
- Because of the decrease in the irregularities on the polished surface
- Because of the shiny coating on the surface
- Because of the increase in irregularities on the polished surface
- Both (2) and (3)
Which of the following is/are used to provide a better grip to tyres?
- Smoothening of wheels
- Oiling
- Treading of wheels
- Both (1) and (2)