Physics
Fill in the blanks:
(a) Work is said to be done by a force only when …………… .
(b) Work done = Force x …………… .
(c) The energy of a body is its capacity to do …………… .
(d) The S.I. unit of energy is …………… .
(e) The potential energy of a body is due to its …………… and kinetic energy of a body is due to its …………… .
(f) Gravitational potential energy U = mass x force of gravity on unit mass x …………… .
(g) Kinetic energy = x mass x …………… .
(h) Power P = …………… / time taken.
(i) The S.I. unit of power is …………… .
(j) 1 H.P. = …………… W.
Work, Energy & Power
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Answer
(a) Work is said to be done by a force only when the body moves.
(b) Work done = Force x distance moved in the direction of force.
(c) The energy of a body is its capacity to do work.
(d) The S.I. unit of energy is joule .
(e) The potential energy of a body is due to its state of rest or position and kinetic energy of a body is due to its state of motion.
(f) Gravitational potential energy U = mass x force of gravity on unit mass x vertical height.
(g) Kinetic energy = x mass x (speed)2.
(h) Power P = Work done by the body / time taken.
(i) The S.I. unit of power is watt (W).
(j) 1 H.P. = 746 W.
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Related Questions
Assertion (A) : The power spent in doing a work remains the same, even if the same work is done in a lesser time.
Reason (R) : The power spent by a source depends on the time taken by the source to do that work.
- Both A and R are true and R is the correct explanation of A
- Both A and R are true and R is not the correct explanation of A
- Assertion is true but reason is false
- Assertion is false but reason is true
Assertion (A) : When a ball is dropped from a height, its kinetic energy decreases and potential energy increases.
Reason (R) : The total mechanical energy remains conserved during the fall, if we ignore air resistance.
- Both A and R are true and R is the correct explanation of A
- Both A and R are true and R is not the correct explanation of A
- Assertion is true but reason is false
- Assertion is false but reason is true
Write true or false for each statement:
(a) A coolie does no work against the force of gravity while carrying a luggage on a plane road.
(b) The energy stored in water of a dam is kinetic energy.
(c) The energy of a flying kite is kinetic energy.
(d) Work done by a boy depends on the time in which he does work.
(e) Power spent by a body depends on the time for which it does work.
Match the following:
Column A Column B (a) A stone at a height (i) power (b) A moving ball (ii) joule (c) Energy (iii) work done in 1 sec (d) Power (iv) potential energy (e) watt (v) kinetic energy