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Work is said to be done, if a force(F) causes a displacement in a body in the direction of force.

Work and Energy. Work. Work is said to be done, if a force(F) causes a displacement in a body in the direction of force. . Let the object be displaced through a distance, s in the direction of the force, F. Contd. Work and Energy. Work. Work done (W) =force × displacement

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Work is said to be done, if a force(F) causes a displacement in a body in the direction of force.

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  1. Work and Energy Work Work is said to be done, if a force(F) causes a displacement in a body in the direction of force. Let the object be displaced through a distance, s in the direction of the force, F. Contd.

  2. Work and Energy Work Work done (W) =force × displacement = F s Work is a scalar quantity. The SI unit of work is Joule.

  3. Work and Energy Categories of work Positive Work If force and displacement are in the same direction, work will be positive or if  = 0 or  < 90°.

  4. Work and Energy Categories of work Zero Work If force and displacement are perpendicular to each other, work will be zero. since  = 90°Work = 0as Work = Fd Cos Work = Fd Cos 90° Work = (F)(d)(0) Work = 0

  5. Work and Energy Categories of work Negative Work If force and displacement are in the opposite direction, work will be negative. since  = 180°Work = - veas Work = Fd Cos Work = Fd Cos 180° Work = (F)(d)(-1) Work = -Fd

  6. Work and Energy Assessment Example A force of 8 N is acting on an object. The object is displaced through 4 m in the direction of the force. Find the work done. Solution Force applied on object, F = 8 N displacement, s = 4 m If the force acts on the object all through the displacement, then work done = F × s W= 8 N × 4 m =32 N m or 32 J

  7. Work and Energy Assessment Example A porter lifts a luggage of 25 kg from the ground and puts it on his head 2.5 m above the ground. Calculate the work done by him on the luggage. Solution Mass of luggage, m = 25 kg and displacement, s = 2.5 m. Work done, W = F × s = mg × s = 25 kg × 10 m s-2 × 2.5 m = 625 kg ms-2 m = 625 N m = 225 J

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