Q I. Answer in one word:
1. Friction depends on the -------- of the surface.
2. The energy required to overcome friction is mainly converted into -----
3. What is the cause of friction?
4. When does friction come into play?
Q II. Answer in brief: -
5. Suppose your writing desk is tilted a little. A book kept on it starts sliding
down. What is the direction of frictional force acting on it? Explain.
6. You spill a bucket of soapy water on a marble floor accidentally. Would it
make it easier or more difficult for you to walk on the floor? Why?
7. Give two advantages and disadvantages of friction.
Answers
Answer:
1. smoothness or roughness
2. heat energy
3. Friction is caused by the interlocking of irregularities in the surface of two objects which are in contact with each other
4. Friction comes into play when irregularities present in the surfaces of two objects in contact get interlocked with each other
5. Frictional force always acts as opposite to the direction of motion. Force of friction will be always parallel to the two surfaces in contact. Thus, the direction of frictional force acting on the book is parallel to the tilted table & opposite to the direction of sliding of a book.
6. It is difficult to walk because when soapy water falls on the floor then the friction between the feet and floor reduces significantly. Thus, the feet will not get the proper grip on the floor and the chances to slip increases.
7. ADVANTAGES
Friction enables us to walk freely.
Objects can be piled up without slipping
DISADVANTAGES
Friction slows down motion
It reduces the efficiency of a machine
Explanation: