class 9th Physics practice sats

 

                      Subject:- Physics (Work, Energy & Power)

Description:-  Here you can see subjective questions for practice only. Section –A contains ‘work type questions’, section – B contains ‘energy type Questions & section –C contains ‘Power type Questions’ respectively.

1.       When is work said to be done?

2.       Define the SI Unit of work done.

3.       Define 1 Joule.

4.       State the reason, why work is a scalar quantity?

5.       Calculate the work done by a man rotating a wheel and an amusement slide a fair 40 times in one minute.

6.       Define: (a) Positive work done (b) Negative work done

7.       Give an example for each:

(a)    Zero work done

(b)   Positive work done

(c)    Negative work done

8.       In which of the following case work is said to be done?

(a)    When we push a table.

(b)   When a person holds a book in his hand and keeps it stationary.

(c)    When a wire is twisted.

9.       What will be the the nature of work done when force acting on a body retards its motion justify your answer by quoting examples.

10.   Find the work done by a body experiencing circular motion.

11.   What amount of work is done by a man of height 2m standing on a bus terminus holding a 25 kg trunk on his head?

12.   Calculi the amount of work done in  the following cases with proper reasoning:

(a)    An electron revolving around the nucleus in circular orbit of radius ‘r’.

(b)   A body of mass ‘m’ freely falling under the gravity from the top of a building of height ‘h’.

13.    A worker lifts a load to a building of height ‘h’ by applying force in the same direction displacing the load under the gravity.

(a)    In which direction does the force of gravity acts?

(b)   Which one of these forces is doing positive work? Give reason.

14.   A man is sitting on a bench and thinking about ideas meant for planning for his friend’s birthday . what work is done by him in his planning’s?

15.   When an object is thrown upward with certain angle moving in a curved path, it falls back on the ground. The initial and final positions of the path of the object lie on the same horizontal line. How much work is done by the force of gravity on the object?

Energy 

1.     Define energy.

2. state the law of conservation of energy.

3. state the SI unit of energy.

4. which type of energy does a moving object posses?

5. state the different forms of energy.

6. find out the relation between J and Erg.

7. what is the sum of kinetic energy and potential energy of a body collectively called?

8. Drive an expression for potential energy of a body with mass ‘m’ and placed at height ‘h’.

9. Drive an expression for kinetic energy possessed by a body of mass ‘m’ moving with a speed ‘v’.

10. Define dissipation of energy.

11. kinetic energy of a moving body could be negative.

12. Is the above statement correct? Explain.

13. during the oscillation of a pendulum at what stage of potential and kinetic energy are maximum?

14. By changing mass or Velocity of a body which will cause greater change in kinetic energy of a body ?

15. A body is having Momentum P = 0 with it have mechanical energy. Explain.

16. A body of mass ‘m’ is moving with a velocity ‘v’ Express kinetic energy in terms of ‘m’ and ‘v’.

17. sun is the ultimate source of energy. Explain how it provides energy for flowing water.



18. On a heap of sand , two identical objects made of iron are allowed to fall from the same height. It was observed that the iron objects penetrates more in the sand than the wooden object. Which one of the two has more potential energy?