# Work and Energy (Practice Sheet, Class 9)

(1) If a force of 10 N applied on an object, it displaced 8 m in the direction of the force applied. Calculate work done on the object.

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(2) Define energy?

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(3) What does a “unit” means?

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(4) An electric bulb of 60 w is used for 3 hours per day. Calculate the “units” of energy consumed in one day y the bulb.

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(5) An object of mass 100 kg starts moving at velocity 10 m/s. It velocity increases to 20 m/s. Calculate its kinetic energy?

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(6) In which fig given below work done will be greater. Solution-

(7) What is the energy transformation in stretched bow and arrow?

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(8) There are two children A and B. Both weigh same. They climb a rope of 8 m. Child A completes climbing in 10 second while child B completes climbing in 5 second.

(i) Who has done more work?

(ii) Who has done more work in 1 second?

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(9)Find the potential energy of the object whose mass is 18 kg. The object is at the 10 m height. (Take g = 10 m/s2)

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(10) A porter carry 10 kg load on its head and stand at a place for half an hour and waiting for the train. Another porter also carry 10 kg load and walk 100 m distance. Which porter has done work and why?

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Helping Topics

Work and energy

NCERT solutions, class 9 