Questions
Two surfaces A and B have a static friction of 100 N. Which of the following can be the sliding friction between A and B?
- 110 N
- 90 N
- 115 N
- 150 N
- 145 N
A porter is pushing a big suitcase on the ground from north to south direction. The force of friction due to ground will act on this big suitcase towards ______.
- west direction
- east direction
- south direction
- north direction
- None of these
Which of the following can be measured with a spring balance?
a. Weight of an object
b. Density of an object
c. Mass of an object
d. Force acting on an object
- Only a and b
- Only b and c
- Only a and c
- Only b and d
- Only a and d
The friction between two surfaces depends on which of the following factors?
a. The force of gravity of Earth.
b. The smoothness or roughness of the two surfaces.
c. The force with which the two surfaces are pressed together.
- Only a
- Only a and b
- Only b
- Only b and c
- Only c
Which of the following statements is/are false?
a. The interlocking of irregularities of the two surfaces opposes the motion of one object over the other and gives rise to force of friction.
b. Vehicles are able to move on road because of the presence of friction between their tyres and the surface of road.
c. Cars and speedboats are streamlined to increase drag.
- Only a
- Only a and b
- Only b
- Only b and c
- Only c
Which of the following should be applied to a carrom board to reduce friction?
- A dry lubricant
- A layer of grease
- A ball bearing
- A lubricating oil
- None of these
Which of the following will produce maximum friction?
- If one rubs sand paper on a polished marble top
- If one rubs sand paper on a glass top
- If one rubs sand paper on another sand paper
- If one rubs sand paper on a wet floor
- If one rubs sand paper on an aluminium frame
What will be the magnitude of the friction force on an object when it just starts moving?
a. Sliding friction
b. Rolling friction
c. The maximum value of static friction
- Only a
- Only a and b
- Only b
- Only b and c
- Only c
If static friction between two surfaces is 10 N, then the rolling friction between these two surfaces will most likely be
- 20 N
- 8 N
- 15 N
- 22 N
- 40 N
The magnitude of drag exerted by a fluid on an object does not depend on which of the following factors?
- Nature of the fluid
- Size of the object
- Speed of the object
- Shape of the object
- Volume of the fluid
Five similar cars A, B, C, D and E, having the same mass, were running at the same speed on the same road when brakes were applied. All the cars came to a stop after covering distances of 7 m, 9 m, 12 m, 14 m and 17 m, respectively. In which of the following cars was the friction between the brake pads and discs the minimum?
- A
- B
- C
- D
- E
Which of the following statements is/are false?
a. It is easier to hold an earthen pot in our hand than a glass tumbler.
b. Higher the viscosity of fluid, lesser will be the drag action on an object moving through it.
c. Applying oil helps in avoiding interlocking between two surfaces to a large extent.
- Only a
- Only a and b
- Only b
- Only b and c
- Only c
In cases where friction is useful, one wants to increase it. Which of the following is not a method to increase friction?
- By making treads in the tyres of vehicles
- By providing spikes in the shoes of players
- By making soles of shoes smooth
- By using some coarse substance on the hands of a gymnast
- By using sledges instead of trolleys with wheels
In most of the machines, friction is reduced by using ball bearings. Ball bearings convert
- sliding friction into rolling friction
- static friction into rolling friction
- sliding friction into static friction
- rolling friction into sliding friction
- rolling friction into static friction
Which of the following statements is/are false?
a. It is easier to move an object by sliding than by keeping it on rollers.
b. Friction can be reduced but not eliminated completely.
c. Fluid friction reduces the speed of the objects moving through a fluid.
- Only a
- Only a and b
- Only b
- Only b and c
- Only c