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प्रश्न
उत्तर
P.E. is the energy possessed by a body by virtue of its position, shape or configuration but K.E. is the energy possessed by a body by virtue of its velocity or motion.
E.g. A ball kept on a cliff possesses P.E. but as soon as it is kicked it possesses K.E.
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संबंधित प्रश्न
A pair of bullocks exerts a force of 140 N on a plough. The field being ploughed is 15 m long. How much work is done in ploughing the length of the field?
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?
In each of the following a force, F is acting on an object of mass, m. The direction of displacement is from west to east, as shown by the longer arrow. Observe the diagrams carefully and state whether the work done by the force is negative, positive or zero.
1 J = ______ calorie.
Find the kinetic energy of a body of mass 1 kg moving with a uniform velocity of 10 m s-1.
A force of 50 N acts on a body and moves it a distance of 4 m on horizontal surface. Calculate the work done if the direction of force is at an angle of 60° to the horizontal surface.
The work done on an object does not depend on ______.
What is meant by a translational motion? Give one example.
What is the ratio of SI units to CGS units of 'work'?
A woman pulls a bucket of water of total mass 5 kg from a well which is 10 s. calculate the power used by her.
(a) Define power and name its unit.
(b) A girl weighting 50 kg climbs up 60 steps each of 20 cm height in 5 minutes. Calculate the power developed.
How fast should a boy weighting 30 kg run so that his kinetic energy is 375 joule?
Give an example
Electrical energy changes to heat energy.
A girl of mass 40 kg runs a height of 80 stairs, each 25 cm high with a load of 20 kg on her head in 25 sec. If g is 10 m/s2, find:
(i) Gravitational force acting on the girl.
(ii) Work done by her.
(iii) Useful work done by her.
(iv) Her power in watt.
________ is said to be done when a force is acting on it.
Look at the activity below. Reason out whether or not work is done in the light of your understanding of the term ‘work’.
Suma is swimming in a pond.
