Machines -- Ch. 7 Resource

Paul Hewitt talks to his students about a pulley (why it is a machine).

He says "and that piano is going up in the air. How can be such a thing? Well first of all, if the pulley system means that the piano is being held by ten ropes...he's pulling one of those...so he's got one-tenth the weight of the piano on every rope -- the one he's pulling!"

Watch and learn WHY we can use a pulley to lessen our workload input:



On the chalkboard behind Hewitt, it's written that WORK = Δ ENERGY

• Work = force x distance
• Machines: Work input = Work output
• (force)(distance)in = (force)(distance)out

The force input is the amount of force you use to push/pull the object.
The distance input is how far you push/pull when you exert the force on it.

The force output is the original weight of the object.
The distance output is how far the object actually goes when the force acts on it.

ENERGY CANNOT BE CERATED NOR DESTROYED, THEREFORE YOU CANNOT GET MORE WORK OUT OF A MACHINE THAN YOU PUT IN. 

A MACHINE SIMPLY DISTRIBUTES THE FORCE (INPUT) OVER A LARGER DISTANCE, MAKING THE WORK INPUT EASIER.

THE WORK IN AND WORK OUT MUST BE EQUAL!!


CHEERS.