Physics - Chapter 11: Work and Machines

work

the transfer of energy from one body to another; an effort that produces motion

Joule

the SI unit of work

Foot pound

the U.S. Customary unit of work

W \= Fd

equation for work (horizontal)

W\= Fdcos(theta)

Equation for work ( angled)

net work

the sum of positive and negative work

negative work

force applied opposite to motion

power

the time rate of doing work

p \= W/t
power \= work/time

equation for power

Watt

SI unit of power

horsepower

method of stating power that has no system of unts

1 hp \= 550 ft.lbs.

1 horsepower to ft. lbs.

fulcrum

the pivot point of any lever

F(i) r(i) \= F(o) r(o)

Law of levers

mechanical advantage

the ability of a machie to multiply force

actual mechanical advantage (AMA)

the ratio of output to input force

ideal mechanical advantage

what mechanical advantage would be if there were no energy losses due to friction or other causes

IMA

the ratio of input to output distance

IMA

which is greater IMA or AMA

Class 1 Lever

the output/ load and the input force are on opposite sides of the pivot point

Class 2 Lever

Output force is between input force and fulcrum

Class 3 Lever

the input is betweenn the fulcrum and output/load

yessir

Know examples of levers on page 165

IMA\= 2(pi)(r) / pitch

IMA equation for a screw

Block and tackle

a series of pulleys working in combination with each other

Wheel and axle

the simplest machine that can be considered a rotary lever

Torque

forces that cause rotation

efficiency

defined as the output work divided by input work or (AMA/IMA)