Alpha Question Bank for Medical: Physics>Chapter 8 - Work, Energy and Power>Exercise-1>Q 115

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A block of mass $m$ is moving with a constant acceleration $a$ on a rough horizontal plane. If the coefficient of friction between the block and plane is $μ .$ The power delivered by the external agent at a time $t$ from the beginning is equal to :

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Important Questions on Work, Energy and Power

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Alpha Question Bank for Medical: Physics>Chapter 8 - Work, Energy and Power>Exercise-1>Q 116

A particle moves with a velocity

\vec{v} = (5 \hat{i} - 3 \hat{j} + 6 \hat{k}) m s^{- 1}

under the influence of a constant force

\vec{F} = (10 \hat{i} + 10 \hat{j} + 20 \hat{k}) N

. The instantaneous power applied to the particle is:

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Alpha Question Bank for Medical: Physics>Chapter 8 - Work, Energy and Power>Exercise-1>Q 117

A man

M_{1}

of mass

80 kg

runs up a staircase in

15 s

. Another man

M_{2}

also of mass

80 kg

runs up the staircase in

20 s

. The ratio of the power developed by them

(P_{1} / P_{2})

will be:

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Alpha Question Bank for Medical: Physics>Chapter 8 - Work, Energy and Power>Exercise-1>Q 118

A car of mass

m

is driven with acceleration

a

along a straight level road against a constant external resistive force

R .

When the velocity of the car is

V,

the rate at which the engine of the car is doing work will be

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Alpha Question Bank for Medical: Physics>Chapter 8 - Work, Energy and Power>Exercise-1>Q 119

An engine pump is used to pump a liquid of density

ρ

continuously through a pipe of cross-sectional area

A .

If the speed of flow of the liquid in the pipe is

v,

then the rate at which kinetic energy is being imparted to the liquid is

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Alpha Question Bank for Medical: Physics>Chapter 8 - Work, Energy and Power>Exercise-1>Q 120

Power of a water pump is

2 kW

. If

g = 10 m s^{- 2}

, then the amount of water that can raise in

1 minute

to a height of

10 m

is

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Alpha Question Bank for Medical: Physics>Chapter 8 - Work, Energy and Power>Exercise-1>Q 121

A car of mass

1250 kg

is moving at

30 m s^{- 1}

. Its engine delivers

30 kW

while resistive force due to surface is

750 N

. What max acceleration can be given in the car

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Alpha Question Bank for Medical: Physics>Chapter 8 - Work, Energy and Power>Exercise-1>Q 122

A body is moved along a straight line by a machine delivering constant power. The distance moved by the body in time

t

is proportional to

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Alpha Question Bank for Medical: Physics>Chapter 8 - Work, Energy and Power>Exercise-1>Q 123

A body of mass

m

, accelerates uniformly from rest to

v_{1}

in time

t_{1}

. The instantaneous power delivered to the body as a function of time

t

is