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प्रश्न
उत्तर
Four different forms of energy:
(i) Solar energy
(ii) Mechanical energy
(iii) Wind energy
(iv) Nuclear energy
APPEARS IN
संबंधित प्रश्न
Explain briefly why the work done by a fielder when he takes a catch in a cricket match is negative.
A force acts on a body and displaces it by a distance S in a direction at an angle θ with the direction of the force. What should be the value of θ to get the maximum positive work?
No work is done by a force if the body
A machine raises a load of 750 N through a height of 16 m in 5 s. calculate:
- energy spent by machine,
- power at which the machine works.
A boy of weight 40 kgf climbs up the 15 steps, each 15 cm high in 10 s and a girl of weight 20 kgf does the same in 5 s. Compare:
- the work done, and
- the power developed by them. Take g = 10 N kg-1.
MULTIPLE CHOICE TYPE
In an electric cell which in use, the change in energy is from:
State the law of conservation of energy.
Write the formula for work done on a body when the body moves at an angle to the direction of force. Give the meaning of each symbol used.
When is the work done by a force on a body : (a) positive, (b) negative, and (c) zero?
Explain by an example that a body may possess energy even when it is not in motion.
Give two examples of couple action in our daily life.
Name the force acting away from the centre of circular path.
Write an expression for the work done against gravity.
Complete the following sentences:
The SI unit of work is ....... and of power is .......
Give an example
Chemical energy changes to heat energy.
A man climbs a slope and another walks same distance on level road. Which of the two expends more energy and why?
