CBSE Class 9 Science Work and Energy MCQs

Question. Water stored in a dam posseses:
(a) No energy
(b) potential energy
(c) kinetic energy
(d) electrical energy

Answer: B

Question. When a body falls freely towards the earth then the total energy
(a) remains constant
(b) increase
(c) decrease
(d) first increases and then decreases

Answer: A

Question. Power of a woman is equal to:
(a) work /time
(b) work /time x work
(c) work x time
(d) time/work

Answer : A

Question. A spring is compresse The P.E of the compressed spring
(a) increase
(b) becomes zero
(c) remains unchanged
(d) decrease

Answer: D

Question. The potential energy of a girl is maximum
(a) standing
(b) sleeping on the ground
(c) sitting on the ground
(d) sitting on the ground

Answer: A

Question. A child on a skateboard is moving at a speed of 2 m/s. After a force acts on the child, her speed is 3 m/s. What can you say about the work done by the external force on the child?
(a) Zero work was done
(b) negative work was done
(c) positive work was done
(d) Infinite work was done

Answer: C

Question. Mike applied 10 N of force over 3 m in 10 seconds. Joe applied the same force over the same distance in 1 minute. Who did more work?
(a) Mike
(b) both did zero work
(c) both did the same work
(d) Joe

Answer: C

Question. Work done by tension in the string when a ball tied to a string is being whirled around in a circle is
(a) tension does no work at all
(b) tension does negative work
(c) tension does positive work
(d) tension does zero work

Answer: A

Question. The value of 1KWH is
(a) 3.6 X 106 J
(b) 3.6 X 105J
(c) 3.6 X 107 J
(d) 3.6 X 109 J

Answer: A

Question. When force acts in opposite direction the work done is
(a) negative
(b) Positive
(c) infinity
(d) Zero

Answer: A

Question. When a spring is compressed work is done on it. Its elastic potential energy
(a) increases
(b) Decreases
(c) Disappears
(d) Does not change

Answer: B

Question. When a body rolls down an inclined plane, then it has
(a) It has no energy
(b) Only Kinetic energy
(c) It has potential energy
(d) Both kinetic and potential energy

Answer: D

Question. On a rough surface a mass is ((a) pulled,((b) pushed by a force acting at an angle with the surface.
(a) Pulling is easier
(b) Pushing is easier
(c) Pushing and pulling both are easier
(d) Pushing and pulling g are not easier

Answer: A

Question. A stone rubbed on a rough surface and placed on the skin will show heating sensation, because
(a) Friction causes heat
(b) Heat cannot flow from the skin to
(c) Heat flows from the stone to skin
(d) Heat cannot flow

Answer: A

Question. Work done by a body from Force-distance curve is
(a) Area under the curve
(b) Slope of the curve
(c) Line parallel to the distance axis
(d) Line parallel to the Force axis

Answer: A

Question. When a body falls freely towards the earth, then its total energy
(a) increases
(b) decreases
(c) remains constant
(d) first increases and then decreases

Answer :   C

Question. In the SI system, the unit of potential energy is
(a) newton
(b) joule
(c) watt
(d) metre per second

Answer :    B

Question. Work done by centripetal force is
(a) >0
(b) ≥0
(c) <0
(d) 0

Answer :   D

Question. What is the commercial unit of energy?
(a) electron volt
(b) W/s
(c) kW h
(d) joule

Answer :   C

Question. When a body like earth is moving in a circular path the work done in that case is zero because:
(a) Centripetal force acts in the direction of motion of the body
(b) Centripetal force acts along the radius of circular path
(c) Gravitational force acts along the radius of circular path
(d) Centrifugal force acts perpendicular to the radius of circular path

Answer :   B

Question. 9800 joule of energy was spent to raise a mass of 50kg, the mass was raised to a height of
(a) 20m
(b) 980m
(c) 10m
(d) none of these

Answer :   A

Question. SI unit of power is
(a) watt
(b) joule
(c) newton
(d) metre

Answer :   A

Question. A girl is carrying a school bag of 3 kg mass on her back and moves 200 m on a levelled road. The work done against the gravitational force will be (g = 10 ms²)
(a) 6 × 10³ J
(b) 6 J
(c) 0.6 J
(d) zero

Answer :   D

Question. Work done by a body is
(a) negative, positive or zero
(b) always positive
(c) always zero
(d) always negative

Answer :   A

Question. A rocket rises up in the air due to the force generated by the fuel. The work done by the:
(a) fuel is negative work and that of force of gravity is positive work
(b) fuel is positive work and that of force of gravity is negative work
(c) both fuel and force of gravity do positive work
(d) both fuel and force of gravity do negative work

Answer :   B

Question. A body is falling from a height h. After it has fallen a height h/2, it will possess
(a) only potential energy
(b) only kinetic energy
(c) half potential and half kinetic energy
(d) more kinetic and less potential energy

Answer :   C

Question. If speed of a car becomes 2 times, its kinetic energy becomes
(a) 4 times
(b) 8 times
(c) 16 times
(d) 12 times

Answer :   A

Question. The form of energy possessed by a flying bird is:
(a) Kinetic energy
(b) Potential energy
(c) Both kinetic and potential energy
(d) Can’t say

Answer :   C

Question. A ball is dropped from a height of 10 m.
(a) Its potential energy increases and kinetic energy decreases during the falls
(b) Its potential energy is equal to the kinetic energy during the fall.
(c) The potential energy decreases and the kinetic energy increases during the fall.
(d) The potential energy is ‘O’ and kinetic energy is maximum while it is falling.

Answer :   C

Question. The work done is '0' if

(a) The body shows displacement in the opposite direction of the force applied.
(b) The body shows displacement in the same direction as that of the force applied.
(c) The body shows a displacement in perpendicular direction to the force applied.
(d) The body masses obliquely to the direction of the force applied.

Answer :   B

Question. Work done by the gravitational force of earth on a satellite along a circular path is
(a) O
(b) minimum
(c) max
(d) all of these

Answer :   A

Question. A body is falling from a height h. After it has fallen to a height of h/2, it will possess:
(a) Only kinetic energy
(b) Half kinetic and half potential energy
(c) Only potential energy
(d) More kinetic and less potential energy

Answer :   D

Question. When speed of the moving object is doubled its
(a) Acceleration is doubled
(b) Momentum becomes four times more
(c) K E. is increased to four times
(d) Potential energy is increased

Answer :   C