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9th Manipur Board
IMPORTANT
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When do we say that work is done by a force?

Important Questions on Work, Energy and Power

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9th Manipur Board
IMPORTANT
Science for Class 9>Chapter 9 - Work, Energy and Power>Try to Answer:>Q 2
What is the expression for the work done when a force is acting on an object in the direction of displacement?
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9th Manipur Board
IMPORTANT
Science for Class 9>Chapter 9 - Work, Energy and Power>Try to Answer:>Q 3
What is 1 J of work?
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9th Manipur Board
IMPORTANT
Science for Class 9>Chapter 9 - Work, Energy and Power>Try to Answer:>Q 4
In ploughing a paddy field, a pair of bullocks exerts a force of 200 N together. If the length of field is 50 m, how much work is done (in joules) in the process?
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9th Manipur Board
IMPORTANT
Science for Class 9>Chapter 9 - Work, Energy and Power>Try to answer:>Q 1
What is kinetic energy of an object?
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9th Manipur Board
IMPORTANT
Science for Class 9>Chapter 9 - Work, Energy and Power>EXERCISES>Q 1
Calculate the work done (in joules) by a student in lifting a packet of books of mass 5 kg from the ground and keeping it on a shelf 1.5 m high. (Take g=10 m s-2).
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9th Manipur Board
IMPORTANT
Science for Class 9>Chapter 9 - Work, Energy and Power>EXERCISES>Q 2
A player kicks a ball of mass 500 g placed at the centre of a football ground. The ball leaves his feet with a speed of 4 m s-1. Find the work done by the player on the ball. Does it equal to the kinetic energy of the ball as it leaves?
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9th Manipur Board
IMPORTANT
Science for Class 9>Chapter 9 - Work, Energy and Power>EXERCISES>Q 3

A ball of mass 2 kg is thrown upwards vertically with a speed of 4.9 m s-1. Find the potential energy when it reaches the highest point. Calculate the maximum height it reaches. (Take g=9.8 m s-2).

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9th Manipur Board
IMPORTANT
Science for Class 9>Chapter 9 - Work, Energy and Power>EXERCISES>Q 4
A ball is thrown at a certain angle to the ground. It moves along a curved path and falls back on the ground. The initial and final positions of the path lie on the same horizontal line. What is the work done by the force of gravity on the ball?