CBSE Worksheet for chapter8 Work, Energy & Power class 9
Worksheet For class 9
Find CBSE Worksheet for chapter8 Work, Energy & Power class 9
CLASS9
BOARD: CBSE
Physics Worksheet  8
TOPIC: Work, Energy & Power
For other CBSE Worksheet for class 9 Science check out main page of Physics Wallah.
SUMMARY
 Work – Measurement of work, Units of work done, Energy
 Different forms of energy, Kinetic energy, Potential energy
 Inter conversion of potential and kinetic energy
 Law of conservation of energy, Work energy theorem
 Power – definition and units, Electrical energy and Electrical power
SECTION I – OBJECTIVE

Work done upon a body is:
 A vector quantity
 A scalar quantity
 (A) and (B) both are correct
 None of these

Choose correct relation:
 1 J = 10^{5} erg
 1 J = 10^{7} erg
 1 J = 10^{3} erg
 None of these

Two bodies of mass 1 kg and 4 kg possess equal momentum. The ratio of their K.E.:
 4:1
 1:4
 2:1
 1:2

When you compress a spring you do work on it. The elastic potential energy of spring:
 Increases
 Decreases
 Disappears
 Remain constant

An object of mass 10 kg falls from height 10 m. Kinetic energy gained by the body will be approximately equal to:
 1000 J
 500 J
 100 J
 None of these

A moving body need not have:
 Potential energy
 Kinetic energy
 Momentum
 Velocity

Chlorophyll in the plants convert the light energy into:
 Heat energy
 Chemical energy
 Mechanical energy
 Electrical energy

A weight lifter lifts 240 kg from the ground to a height of 2.5 m in 3 seconds his average power is:
 1960 W
 19.6 W
 1.96 W
 196 W

A body of mass 10 kg is dropped from a point where it possesses energy of 100 J. Then the K.E. when it reaches ground would be:
 1000 J
 100 J
 10 J
 None of these

The power of pump which takes 10 s to lift 100 kg of water to fill a tank situated at height of 20 m is:
 2x10^{4} N
 2x10^{3} W
 2x10^{2} W
 None of these
SECTION II – SUBJECTIVE

Define:
 (i) Work
 (ii) Energy
 (iii) Power
 (iv) Kinetic energy.
 State law of conservation of energy.
 State workenergy theorem.
 What is elastic potential energy?
 A body of mass 10 kg is released from a height 10 m from the ground. After sometime its kinetic energy becomes 450 J. What will be the potential energy of the body at the instant?
 Show that the mechanical energy of freely falling body is conserved.
 What is the work to be done to increase the velocity of a car from 30 km/h to 60km/h, if the mass of the car is 1500kg.
Solutions: to worksheet8 Work, Energy & Power
Objective Problems:
1.(B)  2.(B)  3.(A)  4.(A)  5.(A)  6.(A)  7.(B)  8.(A)  9.(B)  10.(B) 
Subjective Problems
 U = 550 J
 W = 1.56 x 10^{5 }J