Given below are the Class 9 Science Important Questions for work and energy
a) Concepts questions
b) Calculation problems
c) Multiple choice questions
d) Long answer questions
e) Fill in the blank's
1. What do you understand by transformation of energy? Explain with the help of suitable example?
2. List two essential conditions for work to be done?
3. Define energy?
4. Define work? Write an expression of work in terms of force and displacement. State SI unit of work done?
5. Compare the kinetic energies of two objects of masses 10kg anf 50kg respectively but having same momentum?
6. What is a work done on a body moving in a circular path?
7. Identify the state the type of energy transformation in the following cases:
a) Riding a bicycle
b) Burning of cracker
8. Define potential energy? Write an expression for potential energy. Write the SI unit of potential energy?
9. What is work done by the force of gravity on a satellite moving round the earth? Justify the answer?
10. Define kinetic energy? Write an expression for kinetic energy? Write the SI unit of kinetic energy?
11. Define 1 Watt of power? A lamp consumes 1000J of electrical energy in 10s. Calculate its power?
12. Name the two types of mechanical energy? Give two examples when an object possesses both types of energies?
13. Calculate the amount of work required to stop a car of 1000kg moving with a speed of 72km/h?
14. Does the gravitational potential energy of a body depend on the path along which the body is moved, while going from one point to another? Illustrate your answer with the help of suitable example?
15. An object thrown at a certain angle to the ground moves in a curved path and falls back to the ground. The initial and the final points of the path of the object lie on the same horizontal line? What is the work done by the force of gravity on the object?
16. State the kind of energy transformation that takes place in the following devices:
a) Solar battery
b) Electric motor
d) Thermal power plant
e) Hydroelectric power plant
17. Can a body have energy without momentum? Explain?
18. Can a body have momentum without having energy? Explain?
19. Define potential energy? Give SI unit? State two factors on which the magnitude of potential energy depends. Give one example each for the change in potential energy due to:
b) configuration of the body?
20. Calculate the kinetic energy of a car of mass 750kg moving with a velocity of 54km/. Find the new kinetic energy of a car if passenger of mass 50kg sit in the car?
21. Establish a relationship between momentum and kinetic energy of a body?
22. Calculate the kinetic energy of a car of mass 500kg moving with a velocity of 18Km/h. Find the new kinetic energy if two passengers of mass 50 kg each sit in the car?
23. Derive an expression for the kinetic energy of an object?