Work And Energy Test

Work And Energy

This is Work and Energy Test-03 for CBSE class 09 Science.. There are 15 questions in this test with each question having around four answer choices.

Questions & Answers

P. E of your body is maximum when you

A
lie down on the ground
B
are sitting on the chair
C
Are standing.
Correct
D
are sitting on the ground

Statement A: An aeroplane flying at an altitude possesses only K. E. Statement B: An aeroplane flying at an altitude possesses both K. E and P. E. Which of the two statement is true

A
both a and b
B
statement A
C
statement B
Correct
D
none of these

Find the incorrect statement

A
there is no transfer of energy between you and the rock when you push a huge rack and fail to move it
B
body at rest may possess energy
C
the P. E of a freely falling object increases progressively
Correct
D
K.E. is converted into heat and sound energy when a freely falling object eventually stops on reaching the ground

When you compress a coil spring you do work on it. The elastic P. E energy

A
decreases
B
disappears
C
increase
Correct
D
remains unchanged

P.E of a spring increases when it is in the state of

A
compression
B
expansion
C
both a and b
Correct
D
neither a nor b

What happens to the kinetic energy of a freely falling object which eventually stops on reaching the ground?

A
It changes into light energy
B
None of the above
C
It changes in potential energy
D
It changes into heat & sound energy
Correct

Two particles of masses 2g and 4g have equal momentum. What is the ratio between their kinetic energies?

A
3:1
B
2:1
Correct
C
1:3
D
1:2

Statement A: Speed of a gas molecules decreases with increase in temperature Statement B: P. E of the body decreases as it falls towards the surface of the Earth. Which of the two statements is true?

A
statement A
B
statement B
Correct
C
both a and b
D
none of the above

Match the following with correct response. (1) K.E (2) P.E (3) P(4) E(A) mgh (B) \(P \times t\)(C) \(\frac{w}{t}\)(D) \(\frac{1}{2}m{v^2}\)

A
1-A, 2-C, 3-B, 4-D
B
1-C, 2-B, 3-D, 4-A
C
1-D, 2-A, 3-C, 4-B
Correct
D
1-B, 2-D, 3-A, 4-C

Match the following with correct response. (1) Bullet fired from gun (2) A flying bird (3) In a falling stone (4) Water at dam(A) Potential energy changes to kinetic energy (B) Kinetic energy (C) Potential energy (D) Kinetic & Potential energy

A
1-D, 2-A, 3-C, 4-B
B
1-A, 2-C, 3-B, 4-D
C
1-C, 2-B, 3-D, 4-A
D
1-B, 2-D, 3-A, 4-C
Correct

When an object starts to fall freely, which statement is incorrect about it? A Its potential energy is increased and kinetic energy is decreased B Its kinetic energy is increased and potential energy is decreased C Potential energy remains unchanged D Kinetic energy remains unchanged

A
(b) and (c) are correct
B
(a) and (b) are correct
C
All of these
D
(a), (c) and (d) are correct
Correct

An object is falling from a height h, when it has fallen a height h/2, it will possess A Half kinetic energy B Half potential energy C Only kinetic energy D Only potential energy

A
All of these
B
(b) and (c) are correct
C
(a), (b) and (c) are correct
D
(a) and (b) are correct
Correct

Our hands become warm when rubbed against each other. This is because

A
none of these
B
K. E is converted into heat energy
Correct
C
chemical energy is converted into heat energy
D
mechanical energy is converted into heat energy

The head of a nail hammered into the wooden plank becomes hot. This is because of

A
conversion of K. E into heat energy
Correct
B
conversion of mechanical energy into heat energy
C
conversion of chemical energy into heat energy
D
All of the above.

“Lever transforms mechanical energy into muscular energy” the above statement is

A
false
Correct
B
true
C
partially true
D
partially false