Question 1 :
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In the above fig. A force of 5 N is acting on an object. The object is displaced through 2 m in the direction of the force. If the force acts on the object all through the displacement, then what is the work done?
Question 2 :
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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 3 :
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 4 :
The work done on an object does not depend upon the
Question 5 :
An iron sphere of mass 10 kg has the same diameter as an aluminium sphere of mass is 3.5 kg. Both spheres are dropped simultaneously from a tower. When they are 10 m above the ground, they have the same
Question 6 :
Calculate the work required to be done to stop a car of 1500 kg moving at a velocity of 60 km/h?
Question 7 :
What are the two conditions that are really essential for a work to be done?
Question 8 :
The sum of the potential energy and kinetic energy of the object would be the same at all points. That is, potential energy + kinetic energy = constant.
Question 9 :
Work done on an object is defined as the magnitude of the force multiplied by the distance moved by the object in the direction of the applied force. The unit of work is joule:$ 1 joule = 1 newton \times 1 metre.$ Is the statement true or false?
Question 10 :
If an agent does a work W in time t, then power is given by: _________.
Question 11 :
Certain force acting on a 20 kg mass changes its velocity from 5 $\frac{m}{s}$to 2 $\frac{m}{s}$. Calculate the work done by the force.
Question 12 :
An electric bulb of 60 W is used for 6 h per day. Calculate the ‘units’ of energy consumed in one day by the bulb.
Question 14 :
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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 15 :
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 17 :
Can there be displacement of an object in the absence of any force acting on it?
Question 18 :
Write an expression for the work done when a force is acting on an object in the direction of its displacement.
Question 19 :
If the object is starting from its stationary position, that is, u = 0, then work done, W = ?
Question 20 :
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 doubled?
Question 21 :
Is it possible that an object is in the state of accelerated motion due to external force acting on it, but no work is being done by the force.
Question 22 :
A lamp consumes 1000 J of electrical energy in 10 s. What is its power?
Question 23 :
A certain household has consumed 250 units of energy during a month. How much energy is this in joules?
Question 24 :
Four men lift a 250 kg box to a height of 1 m and hold it without raising or lowering it. How much work is done by the men in lifting the box? $(g=10 ms^{-2})$