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Work. Work. Definition… Work: The product of the force exerted on an object and the distance through which the object moves When work is done energy is transferred! Joule: The SI unit of work and of all other forms of energy
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Work • Definition… • Work: The product of the force exerted on an object and the distance through which the object moves • When work is done energy is transferred! • Joule: The SI unit of work and of all other forms of energy • One joule of work is done when a force of one newton is exerted on an object moved one meter in the direction of the force
Work • Two things are involved in every case where work is done • The application of a force • The movement of something by that force • Examples: • Pushing on a wall • Lifting a box • Pushing a box across the floor
Work • The force and the distance must be in the same direction, if they are perpendicular then no work is done. • Examples: • Picking up a box and carrying it to another location • Pulling a child on a sled
Work • Calculation: A 100N box is carried 3m up a flight of stairs. How much work is done? F=100N d=3m Work = Force x Distance W=100N x 3m = 300Nm
Work • Units: • Newton meters (Nm) • A newton is equal to a kgm/s2 • A newton meter is equal to kgm2/s2 • We call a Nm or a kgm2/s2a joule • Named after British scientist James Joule • The symbol for a joule is (J) • A joule is the SI unit for work and for all types of energy