Question 1 :
Calculate the work required to be done to stop a car of 1500 kg moving at a velocity of 60 $\frac{km}{h}$.
Question 2 :
A mass of 10 kg is at a point A on a table. It is moved to a point B. If the line joining A and B is horizontal, what is the work done on the object by the gravitational force?
Question 3 : <img style='object-fit:contain' src='https://teachmint.storage.googleapis.com/question_assets/cbse_ncert/61b1d2e1f59b460d7261f64b.png' />
In the above fig. A force of 7 N acts on an object. The displacement is, say 8 m, in the direction of the force. Let us take it that the force acts on the object through the displacement. What is the work done in this case?
Question 4 :
Write an expression for the work done when a force is acting on an object in the direction of its displacement.
Question 5 :
An electric heater is rated 1500 W. How much energy does it use in 10 hours?
Question 6 :
The kinetic energy of an object of mass m moving with a velocity of 5 $\frac{m}{s}$ is 25 J. What will be its kinetic energy when its velocity is increased three times?
Question 7 :
A porter lifts a luggage of 15 kg from the ground and puts it on his head 1.5 m above the ground. Calculate the work done by him on the luggage.
Question 8 :
A mass of 10 kg is at a point A on a table. It is moved to a point B. If the line joining A and B is horizontal, what is the work done on the object by the gravitational force?
Question 9 :
A donkey is carrying a load on its back. Is it a work?
Question 10 :
A 150 kg car engine develops 500 W for each kg. What force does it exert in moving the car at a speed of $20 ms^{–1}?$
Question 12 :
The kinetic energy of a body moving with a certain velocity is ________ to the work done on it to make it acquire that velocity.
Question 13 :
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?
Question 16 :
What is the work done by the force of gravity on a satellite moving round the earth?
Question 17 :
An object of mass 15 kg is moving with a uniform velocity of 4 $ms^{-1}$. What is the kinetic energy possessed by the object?
Question 18 :
An electric heater is rated 1500 W. How much energy does it use in 10 hours?
Question 19 :
Find the energy in kW h consumed in 10 hours by four devices of power 500 W each.
Question 20 :
A green plant is carrying out photosynthesis. Is it a work?
Question 21 :
A girl is carrying a school bag of 3 kg mass on her back and moves 200 m on a levelled road. The work done against the gravitational force will be ($g=10 ms^{-2}$)
Question 22 :
An object of mass m is moving with a constant velocity v. How much work should be done on the object in order to bring the object to rest?
Question 23 :
An automobile engine propels a 1000 kg car along a levelled road at a speed of $36 kmh^{–1}$. Find the power if the opposing frictional force is 100 N.
Question 24 :
Work done on an object by a force would be zero if the displacement of the object is zero.
Question 25 :
The work done on an object does not depend upon the
Question 26 :
If an electric iron of 1200 W is used for 30 minutes everyday, find electric energy consumed in the month of April.
Question 27 :
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
Question 28 :
A certain household has consumed 250 units of energy during a month. How much energy is this in joules?
Question 29 :
According to the law of conservation of energy, energy can only be transformed from one form to another; it can neither be created nor destroyed. The total energy before and after the transformation always remains constant.
Question 30 :
A wind-mill is lifting water from a well. Is it a work?
Question 31 :
Power is defined as the rate of doing work. The SI unit of power is watt. 1 W = 1 J/s.
Question 32 :
Two girls, each of weight 400 N climb up a rope through a height of 8 m. We name one of the girls A and the other B. Girl A takes 20 s while B takes 50 s to accomplish this task. What is the power expended by each girl?
Question 33 :
Calculate the work required to be done to stop a car of 1500 kg moving at a velocity of 60 km/h?
Question 35 :
An object of mass, m is moving with a constant velocity, v How much work should be done on the object in order to bring the object to rest?
Question 36 : <img style='object-fit:contain' src='https://teachmint.storage.googleapis.com/question_assets/cbse_ncert/61b1d2b5f59b460d7261f610.JPG' />
In the given figure, a boy is moving on a straight road against a frictional force of 5 N. After travelling a distance of 1.5 km he forgot the correct path at a round about of radius 100m. However, he moves on the circular path for one and half cycle and then he moves forward upto 2.0 km. Calculate the work done by him.
Question 37 :
A ball is dropped from a height of 10 m. If the energy of the ball reduces by 40% after striking the ground, how much high can the ball bounce back? $(g = 10 m s^{–2})$
Question 38 :
The energy used in one hour at the rate of 1kW is called 1 kW h.
Question 40 :
An automobile engine propels a 1000 kg car (A) along a levelled road at a speed of $36 kmh^{–1}$.Now, suppose after travelling a distance of 200 m, this car collides with another stationary car (B) of same mass and comes to rest. Let its engine also stop at the same time. Now car (B) starts moving on the same level road without getting its engine started. Find the speed of the car (B) just after the collision.
Question 41 :
The Jog Falls in Karnataka state are nearly 20 m high. 2000 tonnes of water falls from it in a minute. Calculate the equivalent power if all this energy can be utilized? $(g = 10 ms^{–2})$
Question 42 :
Food grains are getting dried in the sun. Is it a work?
Question 43 :
Certain force acting on a 20 kg mass changes its velocity from 5 m$s^{-1}$ to 2 m$s^{-1}$. Calculate the work done by the force.
Question 44 :
The power of a motor pump is 2 kW. How much water per minute the pump can raise to a height of 10 m? (Given, $g = 10 ms^{-2}$ )
Question 45 :
If the object is starting from its stationary position, that is, u = 0, then work done, W = ?
Question 46 :
A body is falling from a height h. After it has fallen a height $\frac{h}{2}$ , it will possess
Question 47 :
A person holds a bundle of hay over his head for 30 minutes and gets tired. Has he done some work or not?
Question 49 :
Does any work take place when you push a huge rock with all your might and fail to move it?
Question 50 :
The gravitational potential energy of an object at a point above the ground is defined as the work done in raising it from the ground to that point against gravity.
