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Work, Power and Simple Machines. Force 40 N. Work. Distance 10 m. Force acting through a distance. W = F * d = 40 N * 10 m = 400 Joules. Work. Force must be in same direction as distance. Force. Distance. Work. Force must be in same direction as distance.
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Force 40 N Work Distance 10 m Force acting through a distance W = F * d = 40 N * 10 m = 400 Joules
Work • Force must be in same direction as distance Force Distance
Work • Force must be in same direction as distance There is no work being done on the farmer Force Distance
Power 400 J/1 sec = 400 watts 400 J/5 sec = 80 watts How fast (or the rate) Work is done P = W/t
Distance Force Distance Force Distance Force Distance Force How do machines make work easier? Work In Work Out Increase F MA>1 Increase D MA<1 Change direction of F MA=1
Even though machines make work easier, they cannot change the amount of work Work Input Work Output Feffort*distance Fresistance*distance Work Input is always greater than Work Output due to Friction
Even though machines make work easier, Work Input is always greater than Work Output due to Friction % Efficiency = Work Output / Work Input *100 Work Input Work Output Feffort*distance Fresistance*distance 10N*5m= 50J 20N*2m= 40J
Even though machines make work easier, Work Input is always greater than Work Output due to Friction % Efficiency = (40 J / 50 J) = 0.8 Work Input Work Output Feffort*distance Fresistance*distance 10N*5m= 50J 20N*2m= 40J
Even though machines make work easier, Work Input is always greater than Work Output due to Friction % Efficiency = (40 J / 50 J) = 0.8 *100 = 80% Work Input Work Output Feffort*distance Fresistance*distance 10N*5m= 50J 20N*2m= 40J
Inclined Plane A slanted surface used to raise an object
Inclined Plane 5 N 5 N
4 N 5 N Inclined Plane 5 N 5 N Decreases the size of the effort force
4 N 5 N 5 N 5 N Inclined Plane Decreases the size of the effort force
5 N 5 N 4 N 5 N Inclined Plane Decreases the size of the effort force Increases the distance
Wedge An inclined plane that moves
Wedge An inclined plane that moves
Wedge An inclined plane that moves
Wedge An inclined plane that moves
Wedge An inclined plane that moves
Wedge An inclined plane that moves
Wedge As a wedge moves through an object to be cut,
Wedge A small effort force
Wedge A small effort force Is able to overcome
Wedge A small effort force Is able to overcome A large resistance force
Wedge A small effort force Is able to overcome A large resistance force
Wedge How can the mechanical advantage be increased?
Wedge How can the mechanical advantage be increased? Reduce the effort force by decreasing the angle
Screw An inclined plane wrapped around a central bar or cylinder to form a spiral
1st class 2 N 2 N Mechanical Advantage = resistance F / effort F =
1st class 2 N 2 N Mechanical Advantage = resistance F / effort F = 2/2 = 1
1 N 2nd class 2 N Mechanical Advantage = resistance F / effort F =
1 N 2nd class 2 N Mechanical Advantage = resistance F / effort F = 2/1 = 2
3 N 3rd class 2 N Mechanical Advantage = resistance F / effort F
3 N 3rd class 2 N Mechanical Advantage = resistance F / effort F = 2/3 = 0.66
Pulleys Fixed 5 N 5 N Movable
Pulleys Fixed MA = 5/2.5 =2 2.5 N 2.5 N 5 N MA = 5/5=1 5 N 5 N Movable
Pulleys 2.5 N 2.5 N 5 N 5 N 5 N Resistance distance = Effort distance Resistance distance = 1/2 Effort distance
Wheel and Axle • Two circular objects of different size • The wheel always moves a greater distance than the axle
Wheel and Axle • Wheel : Large Distance, Small Force • Axle : Small Distance, Large Force
Inclined Plane? Wedge? Screw? Lever? Pulley? Wheel and Axle? Compound Machine Corkscrew
Inclined Plane Wedge Screw Lever Pulley Wheel and Axle Compound MachineCorkscrew
Inclined Plane? Wedge? Screw? Lever? Pulley? Wheel and Axle? Compound Machine Drill
Inclined Plane Wedge Screw Lever Pulley Wheel and Axle Compound Machine Drill
Inclined Plane? Wedge? Screw? Lever? Pulley? Wheel and Axle? Compound MachineJack
Inclined Plane Wedge Screw Lever Pulley Wheel and Axle Compound MachineJack