A body of mass 5 kg is pulled from point A to B on an inclined plane ABC. A force of 30 N is applied along the surface AB. Calculate, (i) the work done by the force in pulling the body. (ii) the work done against the force due to gravity [ g = 9 . 8 ms - 2 ] (iii) explain the reason for the difference in two works done.

Given, Mass of the body: m = 5 kg Force acting: F = 30 N (i) Work done in pulling the body : W = F . Scosθ θ = 0 ° as the direction of F and S are same. W = 30 × 5 [applying Pythagoras theorem for right angle triangle having sides 1m and 2m respectively] W = 30 5 J . (ii) Work done against the gravity: W = ( mg ) ( h ) . W = mgh W = 5 × 9 . 8 × 1 W = 49 J (iii) The difference in two works done is in case(i) the work is done in pulling the body is against the friction of the inclined plane ABC, when body is pulled from point A to point B with a force of 30 N. In case (ii) we found the work done against the gravity to a height of 1m.

E M B I B E

S CHAND'S ICSE PHYSICS BOOK 2>Chapter 3 - Work, Energy and Power>QUESTIONS>Q 24

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IMPORTANT

Earn 100

Define one kilowatt-hour. Find its relation with joule.

Important Questions on Work, Energy and Power

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IMPORTANT

S CHAND'S ICSE PHYSICS BOOK 2>Chapter 3 - Work, Energy and Power>QUESTIONS>Q 25

A load of 1000 kgf is to be moved on an inclined plane of length 10 m. If the angle of inclination of the plane with the horizontal is

30 °

. Calculate the work done against the gravity.

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

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10th ICSE

IMPORTANT

S CHAND'S ICSE PHYSICS BOOK 2>Chapter 3 - Work, Energy and Power>QUESTIONS>Q 26

A body of mass 5 kg is pulled from point A to B on an inclined plane ABC. A force of 30 N is applied along the surface AB. Calculate,

Question Image

(i) the work done by the force in pulling the body.

(ii) the work done against the force due to gravity $[g = 9.8 {ms}^{- 2}]$

(iii) explain the reason for the difference in two works done.

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IMPORTANT

S CHAND'S ICSE PHYSICS BOOK 2>Chapter 3 - Work, Energy and Power>QUESTIONS>Q 27

A man runs 50m on horizontal road, then 5 m on an inclined road (inclination 3 in 4). Weight of man is 60 kgf. Calculate total work done by him(Neglect friction).

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S CHAND'S ICSE PHYSICS BOOK 2>Chapter 3 - Work, Energy and Power>QUESTIONS>Q 28

An overhead water tank of capacity 1000 litres in 30 m above the ground. Calculate total work done in filling this tank. Calculate total time taken by a lift pump of power 5kW to fill the tank.

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S CHAND'S ICSE PHYSICS BOOK 2>Chapter 3 - Work, Energy and Power>QUESTIONS>Q 29

A steamer boat of 100 HP can move in sea with maximum velocity of 3.43 m/s. Calculate frictional force applied by water on boat.

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S CHAND'S ICSE PHYSICS BOOK 2>Chapter 3 - Work, Energy and Power>QUESTIONS>Q 30

A power lifter lifts a load of 180 kgf up to height of 2.2 m for 5s. Calculate (i) the work done (ii) power developed by him.

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