EASY

Earn 100

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

20% studentsanswered this correctly

Important Questions on Work, Energy and Power

EASY

General Science>Physics>Work, Energy and Power>Power

If the engine of a train of mass

2.05 \times 10^{6} kg

requires a duration of

7

minutes for changing its velocity from

5 m \cdot s^{- 1}

25 m \cdot s^{- 1},

find the power of the engine.

EASY

General Science>Physics>Work, Energy and Power>Power

The heart of a man pumps

5

litres of blood through the arteries per minute at a pressure of

150 mm

of mercury. If the density of mercury be

13.6 \times 10^{3} k g m^{- 3}

and

g = 10 m s^{- 2}

, then the power of heart in watt is:

EASY

General Science>Physics>Work, Energy and Power>Power

A machine gun fires

360

bullets per minute. Each bullet travels with velocity of

500 m s^{- 1}

. If the power of the machine gun is

4.5 kW

then the mass of each bullet is:

EASY

General Science>Physics>Work, Energy and Power>Power

A machine gun fires five bullets per second into a target. The mass of each bullet is

5 gm

. If the average force required to hold the gun in position is

12.5 N

, then what is the speed (S in

m s^{- 1}

) of each bullet & what is the power (

P

kW

) delivered to each bullet?

EASY

General Science>Physics>Work, Energy and Power>Power

A body of mass

m

accelerates uniformly from rest to

v_{1}

in the time

t_{1}

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

EASY

General Science>Physics>Work, Energy and Power>Power

A quarter horse power motor runs at a speed of

600 rpm .

Assuming

60 %

efficiency, the work done by the motor in one rotation is

EASY

General Science>Physics>Work, Energy and Power>Power

An engine develops

20 kW

of power. How much time will it take to lift a mass of

200 kg

to a height of

40 m ? (g = 10 m s^{- 2})

EASY

General Science>Physics>Work, Energy and Power>Power

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

a_{c} = k^{2} r t^{2}

, where

k

is a constant. The power delivered to the particle by the force acting on it is -

EASY

General Science>Physics>Work, Energy and Power>Power

A constant power delivering machine has towed a box, which was initially at rest, along a horizontal straight line. The distance moved by the box in time

t

is proportional to :-

EASY

General Science>Physics>Work, Energy and Power>Power

A body at rest is moved along a horizontal straight line by a machine delivering a constant power. The distance moved by the body in time $t$ is proportional to:

EASY

General Science>Physics>Work, Energy and Power>Power

A car of mass '

m = 1500 kg

' starts from rest and accelerates such that its instantaneous velocity is proportional to

\sqrt{t}

, where t is time in seconds. What should be the instantaneous power delivered to the car if its instantaneous velocity is

20 m s^{- 1}

after

10

seconds.

EASY

General Science>Physics>Work, Energy and Power>Power

Water falls down a

500.0 m

shaft to reach a turbine which generates electricity. How much water must fall per second in order to generate

1.00 \times 10^{9}

watts of power ? (Assume

50 %

efficiency of conversion and

g = 10 m s^{- 1}

)

EASY

General Science>Physics>Work, Energy and Power>Power

Water falls from a

40 m

high dam at the rate of

9 \times 10^{4} kg

per hour. Fifty percentage of gravitational potential energy can be converted into electrical energy. Using this hydro electric energy number of

100 W

lamps, that can be lit, is
(Take

g = 10 {m s}^{- 2}

)

EASY

General Science>Physics>Work, Energy and Power>Power

A water pump rated

600 W,

has an efficiency of

95 % .

If it is used to raise water through vertical distance of

60 m .

The volume of water drawn in

20

minutes, is [Use density of water

= 1000 kg m^{- 3}, g = 10 m / s^{2}

]

EASY

General Science>Physics>Work, Energy and Power>Power

The energy that will be ideally radiated by a

100 kW

transmitter in

1

hour is

MEDIUM

General Science>Physics>Work, Energy and Power>Power

A particle of mass

m

is driven by a machine that delivers a constant power

k

watts. If the particle starts from rest the force on the particle at time

t

is:

MEDIUM

General Science>Physics>Work, Energy and Power>Power

In each heartbeat, a heart pumps

80 m l

of blood at an average pressure of

100 mm

Hg

. Assuming

60

heartbeats per second, the power output of the heart is

(ρ_{H g} = 13.6 \times 10^{3} k g m^{- 3}) (g = 9.8 m s^{- 2})

EASY

General Science>Physics>Work, Energy and Power>Power

Water is pumped steadily out of a flooded basement, at the speed of

10 m s^{- 1}

through a hose (tube) of radius,

1 cm,

passing through a window,

3 m

above the water level. The power of the pump is (Assume

g = 10 m s^{- 2}

, density of water

= 1000 kg m^{- 3}

)

EASY

General Science>Physics>Work, Energy and Power>Power

A body is initially at rest. It undergoes one dimensional motion with constant acceleration. The power delivered to it at time

t

is proportional to

EASY

General Science>Physics>Work, Energy and Power>Power

A body of mass

1 kg

begins to move from rest under the action of a time dependent force

\vec{F} = (2 t \hat{i} + 3 t^{2} \hat{j}) N

, where

\hat{i}

and

\hat{j}

are unit vectors along x and y axis. What power will be developed by the force at the time t?

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

Important Questions on Work, Energy and Power

Learn and Prepare for any exam you want !