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प्रश्न
Give one example in which a force does zero work.
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उत्तर
Work done by the earth on a satellite moving around the earth is zero, as the direction of the motion of the satellite is always perpendicular to the direction of the gravitational force.
संबंधित प्रश्न
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.
Define the term energy.
How is work related to energy?
Give reasons for the following A teacher moving around in the class is doing work but a child standing and reading a book is not doing any work.
MULTIPLE CHOICE TYPE
In an electric cell which in use, the change in energy is from:
Explain degradation of energy by taking two examples of your daily life.
Fill in the blank with suitable word :
Work is measured as a product of __________ and __________
What are the quantities on which the amount of work done depends? How are they related to work?
How much work is done by the gravitational force of earth acting on a satellite moving around it in a circular path? Give reason for your answer.
Complete the following sentences:
The SI unit of work is ....... and of power is .......
A boy of mass m climbs up a staircase of vertical height h.
- What is the work done by the boy against the force of gravity?
- What would have been the work done if he uses a lift in climbing the same vertical height?
Name the physical quantity associated with the 'rate of doing work'.
Name the CGS unit of work.
A boy pulls a box up to 10 m with a force of 5 kgf. Calculate the work done by him.
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.
If a ball is dropped on the sloping roof of a house, it acquires ______ and falls on the ground. That is the transformation of ______ energy into ______ energy takes place.
(kinetic, potential, motion)
