Advertisements
Advertisements
प्रश्न
Define work.
Define the term work
Advertisements
उत्तर
The work done by a force on a body is equal to the product of the force applied and the distance moved by the body in the direction of force i.e.,
Work done = Force × distance moved in the direction of force
APPEARS IN
संबंधित प्रश्न
Write an expression for the work done when a force is acting on an object in the direction of its displacement.
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?
Work done by a boy depends on the time in which he does work.
Power spent by a body depends on the time for which it does work.
Work is said to be done by a forte only when ................
When does a force perform work?
A coolie is moving on a road with a luggage on his head. Does he perform work against the force of gravity? Give reason for your answer.
What are the two kinds of mechanical energy?
1 J = ______ calorie.
Differentiate between energy and power.
A boy of mass 40 kg climbs up the stairs and reaches the roof at a height 8 m in 5 s. Calculate:
- the force of gravity acting on the boy,
- the work done by him against the force of gravity,
- the power spent by boy. (Take g = 10 m s-2)
A body of mass 5 kg falls from a height of 10 m to 4 m. Calculate:
The loss in potential energy of the body,
A bullet of mass 0.5 kg slows down from a speed of 5 m s-1 to that of 3 m s-1. Calculate the change in kinetic energy of the ball.
What is the work done against gravity when a body is moved horizontally along a frictionless surface?
How much work is done when a force of 1 N moves a body through a distance of 1 m in its own direction?
What happens to the work done when the dispacement of body is at right angles to the direction of force acting on it? Explain your answer.
Choose one or more correct alternatives.
For work to be performed, energy must be ______.
- transferred from one place to another
- concentrated
- transformed from one type to another
- destroyed
The work done on an object does not depend on ______.
Name the physical quantity whose SI unit is Nm.
How many joules are there in 1 mega joule?
Give two examples of work done.
Complete the following sentences:
The SI unit of work is ....... and of power is .......
A block of mass 20 kg is pulled up a slope (fig.12) with a constant speed by applying a force of 500 N parallel to the slope. A and B are initial and final positions of the block.
(a) Calculate the work done by the force in moving the block from A and B.
(b) Calculate the potential energy gained by the block.
A girl of mass 50 kg runs up a flight of 40 steps in 20 seconds. If each step in 20 cm high, calculate the power developed by the girl. (g= 10 ms-2).
Give an example
Electrical energy changes of sound energy.
A body of mass 60 kg has the momentum 3000 kgm/s-1. Calculate: the speed of the body.
In the following case write yes, if the work is being done and no if no work is being done.
A boy climbing up a staircase.
Can two agents, doing the same work, have different power?
State larger units of power.
Name the material commonly used for the manufacturing of solar cells.
How long should an electric motor, of power 2 H.P. operate, so as to pump 5 m3 of water from a depth of 15m. [Take g = 10 N kg−1]
A coolie is pushing a box weighing 1500 N up an inclined plane 7.5 m long on to a platform, 2.5 m above the ground.
(i) Calculate the mechanical advantage of the inclined plane. (ii) Calculate the effort applied by the coolie.
(iii) In actual practice, the coolie needs to apply more effort than what is calculated. Give one reason why you think the coolie needs to apply more effort.
Look at the activity below. Reason out whether or not work is done in the light of your understanding of the term ‘work’.
A wind-mill is lifting water from a well.
A car is accelerated on a levelled road and attains a velocity 4 times of its initial velocity. In this process the potential energy of the car
