Questions
Which of the following is a solid lubricant?
- Sand
- Silt
- Oil
- Grease
- Graphite
In which of the following cases is the maximum friction observed?
- A ball hits another ball rolling across the billiards' table.
- A boy dragging a mat on which another boy is seated.
- Holding a greasy tumbler.
- Playing carrom on a board that was sprinkled with powder.
- A boy doing roller skating.
A huge stone has fallen on to a mountain road. A man is clearing out this stone. What is measured as the force required to overcome the friction of this huge stone when he is trying to move it out of the road?
- Sliding friction
- Drag
- Static friction
- Amplitude
- Rolling friction
Rolling friction is lesser than sliding friction. Which of the following correctly represents this phenomenon?
- A boy pushing a huge stone
- Tug of war between two teams
- Ball bearing being used in cycles and fans
- A table being pulled
- A match stick being lit by striking it
A badminton player and an athlete go to a footwear shop. The former selects grooved shoes while the latter selects spiked shoes. What do you think about their selections?
- It is the latest fashion.
- It helps to win matches.
- For giving better blood circulation in their feet.
- To have better grip on the floor.
- To make them look taller.
In which of the following cases is more friction needed?
- Spilling soapy water on a smooth granite floor in the kitchen
- Creaking hinge of a door
- Between machine parts with less grease
- Carroms being struck on a carrom board
- An aeroplane taking off
Which of the following is not a negative effect of friction?
- A child is able to write with a pencil.
- Worn out soles in an old shoe
- Wearing out of tyres of vehicles
- Ball bearing in a machine wearing out
- Machine working for a long time producing too much heat
What term is used for frictional force exerted by air in the atmosphere when an aircraft takes off?
- Sliding friction
- Rolling friction
- Lubrication
- Drag
- Static friction
Which of the following is not an example for streamlined shape?
- Fish
- Tractor
- Aeroplane
- Bird
- Ship
A boy sees a meteorite burning out in the sky. He asks his father about it. His father replies that it happens due to
- wind
- gravity
- friction against air
- rolling friction
- minerals on the meteorite
How does an aeroplane design to reduce fluid friction?
- Powerful engines
- Streamlined shape
- Use of aviation fuel in it
- By reducing the number of passengers in it
- Filling only half the capacity of its fuel tank
________ is the special shape of a body due to which it experiences the least fluid friction.
- Lubrication
- Rolling friction
- Streamlining
- Wear and tear
- Sliding friction
Friction is caused by the _______ on the two surfaces in contact.
- smoothness
- inclination
- height
- irregularities
- width
Which of the following statements is incorrect?
- Friction is a necessary evil.
- Friction cannot be reduced.
- Static friction comes into play when we try to move an object at rest.
- Rolling friction is always less than sliding friction.
- Friction is caused due to interlocking of irregularities on the two surfaces in contact with each other.
A girl was facing a difficulty in removing the bangles she wore on her hands. A suggestion was given to put soap solution on her hands and then try to remove the bangles. This trick worked and she removed the bangles more easily. This was because
- soap solution reduced friction
- soap solution increased the beauty of the bangles
- hand became a bit leaner
- heat was produced
- her skin became harder