# Work and energy 9th class important questions

These are Work and energy 9th class important questions . It is important to practice questions when you finished learning your concepts. It is important from the point of view of your exams. So go ahead and practice these questions . A downloadable file is also available for these questions at the end of the article.

1 Mark short answer questions

1) What is the work done by a force equal to?
2. Name two factors on which kinetic energy depends.
3. What is the commercial unit of energy?
4. Relate 1 kWh with joule.
5. State the law of conservation of energy.
6. Why do we say work done against gravity is negative?
7. What is average power?
8. When the speed of a body is doubled, what is the change in its kinetic energy?
9. What is the difference between potential energy and kinetic energy?
10. What change should be affected in the velocity of the body to maintain same kinetic energy if its mass is increased two times?
11. Difference between between energy and power?
12. A machine does 2060 joule of work in 4 minutes. What is its power?
13. Can a body have energy without momentum?
14. What is the relation between kinetic energy and momentum?
15. Is it necessary for force to do work always?
16. Name two forms of mechanical energy.
17. When is the work done by a force (a) positive (b) negative (c) zero?
18. Give example of Kinetic energy.
19.Which form of energy does the flowing water possess?
20. What is the unit of power?
21.A light and heavy body have equal momenta. Which one has greater kinetic energy?
True and False questions
1) If air resistance is negligible, the sum total of potential and kinetic energies of a freely falling body remains constant
2) Work is a  vector quantity
3) Power is a scalar quantity
4) Momentum is a vector quantity
5) kWh is the unit of power
6) An object moving in a circular orbit. The work done by the centrepetal force acting on the object is non zero
7) kinetic energy of the body can be negative

Fill in the blanks

1)A force acting on a body shows a displacement in the direction normal to the direction of the force. It is said _______ done on the body.

2)A force acting on a body shows a displacement in the direction of the force. It is said _______ is done on the body.

3) Work done is defined as the product of  _____ and ______ in the direction of force.

4) SI Unit of work is  _______.

5) 1  kWh  =   ____  J

6)  Work done on an object is _____ if displacement is zero.

7)  Work done is + when the angle between force and displacement is ____

8)  Work done is i when the angle between force and displacement is ____

9)  Work done against a force is stored as _____.

10) Ability to do work is called _______.

11) Ability of a body to do work due to its position or configuration is known as _________ of the body.

12)  A form of energy an object has because of its motion is called ________.

13) A stretched springs acquires _________(potential/kinetic) energy.

14) Work done against gravity in lifting a mass is stored as ______. Numerically, it is equal to m ×_ ×__.

15) Work done by gravity on a falling body is available as ______ (kinetic/potential) energy on reaching the ground.

16). if mass is m and velocity is v ,then Kinetic Energy = ½ × _ × _

17). If the mass is tripled while its speed remains the same, the kinetic energy will be _____ of the initial kinetic energy.

18). The sum of P.E. and K.E. is called __________.

19) The other name of Nm is

20) A body of mass 6 kg is dropped from the height of 1m. The kinetic energy of the body will be —— when it touches the ground

21) Two objects of masses 2Kg and 3Kg have equal momentum. The ratio of their kinetic energies is …..

22) Two bodies of masses a and b have equal kinetic energies.  If  x and y are their respective momentum, then ratio x : y is ….

23)If the speed of an object is doubled then its kinetic energy is _______

24) The type of energy possessed by a simple pendulum, when it is at the mean position is
25) the physical quantity which is equal to the product of force and velocity is …..

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