11. Fill in the blanks: A. Friction opposes the _____________ between the surfaces in contact with each other. B. Friction depends on the ________________ of surfaces. C. Friction produces ___________________. D. Sprinkling of powder on the carom board_____________ friction. 12. Suppose you are writing on a desk and it gets tilted a little. A book kept on it starts sliding down. Show the direction of frictional force acting on it. 13. You spill a bucket of soapy water on a marble floor accidently. Would it make it easier or more difficult for you to walk on the floor? Why? 14. Explain why sportsman use shoes with spikes. 15. Iqbal has to push a lighter box and Seema has to push a similar heavier box on the same floor. Who will have to apply a larger force and why? 16. Explain why the sliding friction is less than the static friction. 17. Give examples to show that friction is both a friend and a foe. 18. Explain why objects moving in fluids must have special shapes.
Answers
Answered by
4
11.
A.Friction opposes the motion between the surfaces in contact with each other.
B.Friction does not depend on the amount of surface.
C.Friction Produces Heat.
D.Sprinkling of powder on the carom board rolling friction.
12.When a book slides on the writing desk, a frictional force acts between the book and the surface of the desk. The direction of frictional force on the book is opposite to the direction of its motion and acts in upward direction, as shown in the figure alongside.
13.The force of friction pushes it in the forward direction and allows us to walk. The force of friction between the ground and feet decreases when there is soapy water spilled on the floor. Hence, it becomes difficult to walk on the soapy floor.
14. Sportsman use shoes with spikes to increase the force of friction between the shoes and the ground. The increased force of friction give them a better grip while running.
15.Force of friction arises because of interlocking of irregularities on the two surfaces in contact. ... Hence, more force is required to overcome the interlocking. Thus, to push the heavier box, Seema has to apply a greater force than Iqbal.
16.For a given two surface, sliding friction is slightly lesser than that of the static friction because it is easy to move the object which already in motion than the object which is at rest.
17.Friction is friend: (i) Friction allows us to grip and catch different objects. (ii) It helps us to walk comfortably on the surface. (iii) It helps to minimize the speed or to stop the moving objects. ... Friction is foe: (i) Friction causes wear and tear in objects.
18.Objects moving in fluids face the friction of the fluid that opposes their motion. So Objects moving in fluids must have unique shapes called streamlined shapes to reduce the fluid friction.
Attachments:
Similar questions