a block of mass m is suspended by a light thread from a

A block of mass $$m$$ is suspended by a light thread from a lift. The lift is moving upward with uniform velocity $$v.$$ From the frame of lift, the work done by tension on the block in $$t$$ seconds will be
Work Energy and Power mcq question image

Work Energy and Power mcq question image

A. $$ - mgvt$$

B. $$0$$

C. $$\frac{{mgvt}}{2}$$

D. $${mgvt}$$

Answer : $$0$$

Solution :
In the frame of lift displacement is zero,
$${\text{so}}\,\,W = F.S = T.S = 0.$$

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Basic Physics >> Work Energy and Power

Releted Question 1

If a machine is lubricated with oil-

A. the mechanical advantage of the machine increases.

B. the mechanical efficiency of the machine increases.

C. both its mechanical advantage and efficiency increase.

D. its efficiency increases, but its mechanical advantage decreases.

View Answer

Releted Question 2

Two masses of $$1 \,gm$$ and $$4 \,gm$$ are moving with equal kinetic energies. The ratio of the magnitudes of their linear momenta is-

A. $$4:1$$

B. $$\sqrt 2 :1$$

C. $$1:2$$

D. $$1:16$$

View Answer

Releted Question 3

A particle of mass $$m$$ is moving in a circular path of constant radius $$r$$ such that its centripetal acceleration $${a_c}$$ is varying with time $$t$$ as $${a_c} = {k^2}r{t^2}$$ where $$k$$ is a constant. The power delivered to the particles by the force acting on it is:

A. $$2\pi m{k^2}{r^2}t$$

B. $$m{k^2}{r^2}t$$

C. $$\frac{{\left( {m{k^4}{r^2}{t^5}} \right)}}{3}$$

D. Zero

View Answer

Releted Question 4

A spring of force-constant $$k$$ is cut into two pieces such that one piece is double the length of the other. Then the long piece will have a force-constant of-

A. $$\left( {\frac{2}{3}} \right)k$$

B. $$\left( {\frac{3}{2}} \right)k$$

C. $$3k$$

D. $$6k$$

View Answer

A block of mass $$m$$ is suspended by a light thread from a lift. The lift is moving upward with uniform velocity $$v.$$ From the frame of lift, the work done by tension on the block in $$t$$ seconds will be

Releted MCQ Question on
Basic Physics >> Work Energy and Power

If a machine is lubricated with oil-

Two masses of $$1 \,gm$$ and $$4 \,gm$$ are moving with equal kinetic energies. The ratio of the magnitudes of their linear momenta is-

A particle of mass $$m$$ is moving in a circular path of constant radius $$r$$ such that its centripetal acceleration $${a_c}$$ is varying with time $$t$$ as $${a_c} = {k^2}r{t^2}$$ where $$k$$ is a constant. The power delivered to the particles by the force acting on it is:

A spring of force-constant $$k$$ is cut into two pieces such that one piece is double the length of the other. Then the long piece will have a force-constant of-

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Work Energy and Power

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A block of mass $$m$$ is suspended by a light thread from a lift. The lift is moving upward with uniform velocity $$v.$$ From the frame of lift, the work done by tension on the block in $$t$$ seconds will be

Releted MCQ Question on Basic Physics >> Work Energy and Power

If a machine is lubricated with oil-

Two masses of $$1 \,gm$$ and $$4 \,gm$$ are moving with equal kinetic energies. The ratio of the magnitudes of their linear momenta is-

A particle of mass $$m$$ is moving in a circular path of constant radius $$r$$ such that its centripetal acceleration $${a_c}$$ is varying with time $$t$$ as $${a_c} = {k^2}r{t^2}$$ where $$k$$ is a constant. The power delivered to the particles by the force acting on it is:

A spring of force-constant $$k$$ is cut into two pieces such that one piece is double the length of the other. Then the long piece will have a force-constant of-

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