Question

HOTS (Higher Order Thinking Skills) Questions:
1. Rajesh tries to hold a glass with oily hand, it slips from his hand. Give reason for the same.
2. Why does friction damage the machines?
3. Which one is easy to hold, a glass tumbler or an earthen pot in hands? Give reasons.
When you write on a piece of glass sheet with a piece of chalk, the writing is not clear. Explain.
5. Why is it more difficult to pull a boat on the beach than on the sea?
6. Explain why a bicycle can be slowed down by dragging your feet along the ground.
7. Explain why the jar of mixer grinders get hot when the mixer grinder run for a few minutes.
8. Gymnasts apply a coarse substance on their hands. Why?
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Answer 1

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1. Because oil is a lubricant which reduces friction between our hands and glass.

2. The heat generated by friction can disrupts and destroys the part of the machinery.

3. An earthen pot is more easier to hold because a glass tumbler has a smooth surface which has less friction whereas an earthen pot has rough surface which has more friction and thus makes it easy for us to hold.

4. It is difficult to pull the boat on the beach because of the friction between the boat and sand. But in the sea, there is less friction between the sea water and the boat.

5. Because of the friction. when we drag our feet in the ground, the force of friction acts between our feet and the ground and the bicycle stops. ... as a result the bicycle stops.

6. Due to friction & rotation of blades of grinder . during rotation of blade particles collides with wall. As we know that friction produce heat & sound which makes hot the wall of mixer grinder after few minutes of operation.

7. For a better grip

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Hope this helped you☺️

Answer 2

Answer:

1)friction is reduced so it slips from his hands

2) Friction reduces efficiency because when two surfaces slide past each other, friction resists their motion, and in real machines, some input work is always used to overcome friction. The friction generates heat, which is an energy that should be converted in movement.

3) an earthen pot is easy to hold as it is has a rough surface and the friction between hands and the pot will be more in comparison to holding a glass tumbler.

4) as very less friction is generated between chalk and glass so the writing is not clear.

5)It is difficult to pull the boat on the beach because of the friction between the boat and sand. But in the sea, there is less friction between the sea water and the boat.

6) bicycle can be slowed down by dragging our feet along the ground because of the friction. when we drag our feet in the ground, the force of friction acts between our feet and the ground and the bicycle stops.

7)The Jar of a mixer grinder get hot when run for few minutes due to friction & rotation of blades of grinder . during rotation of blade particles collides with wall. As we know that friction produce heat & sound which makes hot the wall of mixer grinder after few minutes of operation

8)Gymnasts apply a coarse substance to their hands for a better grip.