HARD

JEE Advanced

IMPORTANT

Earn 100

An automobile of mass $m$ accelerates, starting from rest, while the engine supplies constant power $P$ . Find its position and instantaneous velocity changes with respect to time.

Important Questions on Work, Energy and Power

HARD

JEE Advanced

IMPORTANT

PHYSICS For Joint Entrance Examination JEE (Advanced) Mechanics I>Chapter 8 - Work, Energy and Power>ILLUSTRATION 8.62

A car of mass $1.0 \times 10^{3} kg$ , starts from rest and maintains an acceleration of $\Rightarrow d s = {(\frac{2 P t}{m})}^{1 / 2} d t$ for $6.0 s$ in the $\Rightarrow \int d s = \int {(\frac{2 P t}{m})}^{1 / 2} d t$ direction as shown in the figure. Assume that a single horizontal force (not shown) accelerates the car. Determine the average power generated by this force.

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HARD

JEE Advanced

IMPORTANT

PHYSICS For Joint Entrance Examination JEE (Advanced) Mechanics I>Chapter 8 - Work, Energy and Power>ILLUSTRATION 8.63

A water pump rated

400 W

has an efficiency of

75 %

. If it is employed to raise water through a height of

40 m

, find the volume of water drawn in

10 \min

HARD

JEE Advanced

IMPORTANT

PHYSICS For Joint Entrance Examination JEE (Advanced) Mechanics I>Chapter 8 - Work, Energy and Power>ILLUSTRATION 8.64>Q (a)

A pump is required to lift

1000 kg

of water per minute from a well

20 m

deep and eject it at a rate of

20 {m s}^{- 1}

.
(a) How much work is done in lifting water?
(b) How much work is done in giving it

K E

?
(c) What HP (horsepower) engine is required for the purpose of lifting water?

EASY

JEE Advanced

IMPORTANT

PHYSICS For Joint Entrance Examination JEE (Advanced) Mechanics I>Chapter 8 - Work, Energy and Power>CONCEPT APPLICATION EXERCISE 8.5>Q 1

A block moves in a uniform circular motion because a cord tied to the block is anchored at the centre of a circle. Is the power of the force exerted on the block by the cord positive, negative, or zero?

EASY

JEE Advanced

IMPORTANT

PHYSICS For Joint Entrance Examination JEE (Advanced) Mechanics I>Chapter 8 - Work, Energy and Power>CONCEPT APPLICATION EXERCISE 8.5>Q 2

What is the power of an engine which can lift

20 metric tonne

of coal per hour from a

20 m

deep mine?

EASY

JEE Advanced

IMPORTANT

PHYSICS For Joint Entrance Examination JEE (Advanced) Mechanics I>Chapter 8 - Work, Energy and Power>CONCEPT APPLICATION EXERCISE 8.5>Q 3

1 kW

motor pumps out water from a well

10 m

deep. Calculate the quantity of water pumped out per second.

EASY

JEE Advanced

IMPORTANT

PHYSICS For Joint Entrance Examination JEE (Advanced) Mechanics I>Chapter 8 - Work, Energy and Power>CONCEPT APPLICATION EXERCISE 8.5>Q 4

One coolie takes

1 \min

to raise a box through a height of

2 m

. Another one takes

30 s

for the same job and does the same amount of work. Which one of the two has greater power and which one uses greater energy?

EASY

JEE Advanced

IMPORTANT

PHYSICS For Joint Entrance Examination JEE (Advanced) Mechanics I>Chapter 8 - Work, Energy and Power>CONCEPT APPLICATION EXERCISE 8.5>Q 5

A large family uses

8 kW

of power. Direct solar energy is incident on the horizontal surface at an average rate of

200 W m^{- 2}

. If

20 %

of this energy can be converted to useful electrical energy, how large an area is needed to supply

8 kW

An automobile of mass m accelerates, starting from rest, while the engine supplies constant power P. Find its position and instantaneous velocity changes with respect to time.

Important Questions on Work, Energy and Power

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An automobile of mass $m$ accelerates, starting from rest, while the engine supplies constant power $P$ . Find its position and instantaneous velocity changes with respect to time.