MEDIUM
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Identify the tense used in this sentence: 'He had been working for three hours before you arrived.'

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Important Questions on Work, Energy and Power

EASY

If the kinetic energy of a particle of mass m, performing uniform circular motion in a circle of radius r, is E, find the acceleration of the particle.

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A force acts on a 2 kg object so that its position is given as a function of time as x=3t2+5. What is the work done by this force in first 5 seconds?
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Two particles A, B are moving on two concentric circles of radii R1 and R2 with equal angular speed ω. At t=0, their positions and direction of motion are shown in the figure:

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The relative velocity VA-VB at t=π2ω is given by:

MEDIUM
A transverse wave travels on a taut steel wire with a velocity of v when tension in it is 2.06×104N. When the tension is changed to T, the velocity changed to v2. The value of T is close to:
EASY
A force of 5 N making an angle θ with the horizontal, acting on an object displaces it by 0.4 m along the horizontal direction. If the object gains kinetic energy of 1J, the horizontal component of the force is
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If Ki and Kf are the initial and final values of kinetic energy of a body respectively, then the work done by the net force on the body is equal to
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A body of mass 1 kg is moving in a vertical circular path of radius 1 m. The difference between the kinetic energies at the highest and lowest position is, 
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A ball of mass m is dropped from a height h on a platform fixed at the top of a vertical spring, as shown in figure. The platform is depressed by a distance x. Then the spring constant is

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EASY
Displacement of an object of mass 2 kg varies as s=3t2+5. Find work done by man from t=0 to t=5 sec.
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The ratio of work done by the internal forces of a car in order to change its speed from 0 to V and  V to 2V is (Assume that the car moves on a horizontal road) -
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The velocity of 2 kg body is changed from (4i^+3j^) m s-1 to 6 m s-1. The work done on the body is
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A block of mass 5 kg is resting on a smooth surface. At what angle a force of 20 N be acted on the body so that it will acquire a kinetic energy of 40 J after moving 4 m ?
EASY
The mass of a particle is 400 times that of an electron and the charge is double. The particle is accelerated by 5 V. Initially, the particle remained in rest, then its final kinetic energy will be
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Consider a car moving along a straight horizontal road with a speed of 72 km h-1. If the coefficient of static friction between road and tyres is 0.5, the shortest distance in which the car can be stopped is
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An inclined track ends in a circular loop of the radius r. From what height on the track a particle should be released so that it completes the loop, assuming there is no friction?

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EASY
A bolt of mass 0.3 kg falls from the ceiling of an elevator moving down with a uniform speed of 7 m s1. It hits the floor of the elevator (length of the elevator = 3 m) and does not rebound. What is the heat produced by the impact? Would your answer be different if the elevator were stationary?
EASY
When work done on a particle is positive
EASY
A particle moves in a straight line with retardation proportional to its displacement. Its loss of KE for any displacement x is proportional to
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If a car is moving on a straight road with constant speed. Then