NEET UG PHYSICS MCQ: WORK-ENERGY-POWER

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Analyzing +4 | -1

Assertion: No work is done by a force on an object when the point of application of the force does not move.
Reason: A small block of mass

m

is kept on a rough inclined surface of inclination

a

fixed in an elevator. The elevator goes up with a uniform velocity

u

and the block does not slide on the wedge. Then the work done by the force of friction on the block in time

t

will be

mgut \sin ^2 \alpha

View answer and explanation

Correct option: B

If both Assertion & Reason are True but Reason is not a correct explanation of the Assertion

Option B is correct because both the assertion and reason are true, but the reason does not explain the assertion. The assertion is about the definition of work, while the reason is about a specific case of friction.

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{A}

ball is dropped on the ground from a height of

2 {~m}

. If the coefficient of restitution is 0.6 , the height to which the ball will rebound is A running man has the same kinetic energy as that of a boy of half his mass. The man speed up by

2\mathrm{\;m}{\mathrm{s}^{ - 1}}

and the boy changes his speed by

x = \mathrm{m}{\mathrm{s}^{ - 1}}

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\mathrm{m}{\mathrm{s}^{ - 1}}

is A force

\mathrm{\vec F} = - K\left( {y\hat i + x\hat j} \right)

(where K is a positive constant) acts on a particle moving in the x-y plane. Starting from the origin, the particle is taken along the positive x-axis to the point (a,0) and then parallel to the y-axis to the (a,a). The total work done by the force

\mathrm{\vec F}

on the particle is A motor is used to deliver water at a certain rate from a given pipe. To obtain 3 times water from same pipe in same time, by what factor should power of the motor be increased. A body projected vertically from the earth reaches a height equal to earth’s radius before returning to the earth. The power exerted by the gravitational force is greatest The speed limit of a car over a roadways bridge in the form of a vertical arc is

9.8\;\mathrm{m}{\mathrm{s}^{ - 1}}

. The diameter of the are is