Monday, April 27, 2015

Learnwell science class 8 chapter force and pressure n Friction

High order thinking skill [HOTS Questions]

Learnwell science class 8

1. Why are women advised not to wear high heeled shoes?

Ans: High heeled shoes do not distribute weight of body over the surface of and therefore women may fall on the ground due to less grips on ground. This is why women are advised not to wear high heeled shoes.

2. It is more difficult to pull boat on the beach than on the water?

Ans: Liquid and gases exert lesser friction as compared to solid surfaces. Therefore, boat on the beach experience more friction than on the water. Thus, it is more difficult to pull boat on the beach than on the water.

3. How are you able to drink juice using a straw?

Ans: When we suck air from straw the air pressure in the straw decreases that is enough to pull the juice. Air pressure pull the juice to move up inside the straw into our mouth .

4. Why is the tip of sewing needle sharp?

Ans: The sharp tip of sewing needle sharp distributes force over less are so that more pressure created on the clothes. This makes work with needle easier.

5. Why are powder sprinkled on the carom board before playing?
Ans: Powder sprinkled on the carom board before playing to reduce friction between coins and surface of carom board.

6. Why does a woman apply soap solution on their hand to put on bangles?
Ans: A woman apply soap solution on their hand to reduce friction so that it became easier to put on bangles .

7. Does the shoes having spikes on their sole help in making better grip on ice?
Ans: Yes, spikes increase friction and help to have better grip on ice.

8. Will a match stick catch fire when it is rubbed against cemented wall?

Ans: Yes. A match stick catches fire when it is rubbed against cemented wall because force of friction raises the temperature of match stick head.

9. What would happen if there is no friction?

Ans: Friction is the force that opposes the motion of every object. So if there is no friction then, there would be nothing to stop a moving object, and it would continue to move forever

10. Machine parts are oiled occasionally?

Ans: Lubricant like oil and grease form layer between the two moving surfaces so that they cannot directly rub each other. This make the movement smoother.

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