1. Which surface has more irregularities?
a. Smooth b. Rough
c. Transparent d. None of these
2. Which of the following is produced due to friction between moving parts of machine?
a. Light b. Sound
c. Electricity d. Heat
3. A toy car released with the same initial speed will travel farthest on __________ surface.
a. Muddy b. Polished marble surface
c. Cemented surface d. Brick surface
4. If we apply oil on door hinges, the friction will
a. Increase b. Decrease
c. Disappear altogether d. Will remain unchanged
5. Fluid are____
a. Gases b. Liquids c. Gases and liquids both d. None of these 6 . Which of the following statements are incorrect?
a. Friction acts on a ball rolling along the ground
b. Friction acts on a boat moving on water
c. Friction acts on a bicycle moving on a smooth road
d. Friction does not act on a ball moving through air
7. Give reasons
a. Sportsmen use shoes with spikes
b. Oil is applied to the moving part of a machine
c. Wheels of a car are made circular
d. Asteroids/meteors get burnt on entering earth's atmosphere .
8. On what principle do ball bearings work?
9. A ball set rolling on the floor. Will it stop by itself? Why?
Answers
Answer:
answer of 1 is option b
2is d
3is d
4 is b
5 is c
6 is d
after it so long
I hope this answers are useful to you
The answer to the given questions are as follows :
1. Rough
=> Rough surface has the most friction among the three of them. Due to which it has more irregularities.
2. Heat
=> Due to the presence of friction between our hands, when we rub it together we feel the heat.
3. Polished marble surface
=> It has the least inertia due to which motion of the toy car is not opposed much. Also friction present is less compared to other surfaces.
4. Decrease
=> Oil acts as a lubricant which decreases friction between hinges and door.
5. Gases and liquids both
=> Fluids are a mixture of gases and liquids. It can flow like a liquid and also have characteristics of gases.
6. Friction does not act on a ball moving through the air
=> Friction does act on a ball moving through the air. It is known as air resistance.
7. a. To get more grip while running, sportsmen use shoes with spikes. It provides more friction between shoes and ground
b. Oils act as lubricants. So to decrease friction between moving parts of the machine oil is applied.
c. Wheels of the car has a circular shape so that minimum friction acts between wheels and the ground.
d. Due to large friction acting on asteroids/meteors, heat gets produced and it starts burning
8. Principle used in a ball bearing is friction. The ball in the wheel decreases friction between the inner and outer cylinder
9. A ball set rolling on the floor. After some time, it stops rolling. The reason for this is the friction present on the floor which acts on the ball and opposes its motion.