1. Why we use machines

2. Machine- device that makes work easier.
2 forces are involved when machine is used
Effort force (Fe) The force applied to the machine.
Resistance force (Fr) The force applied by the machine.

3. Ex: You apply effort force to a crowbar handle
Ex: You apply effort force to a crowbar handle. The crowbar handle has resistance force on lid to crate.

4. There’s 2 kinds of work when a machine is used
Work input (Win) Work done on the machine
Work output (Wout) Work done by the machine

5. To calculate Work input
Win= Fe X de
(Win = effort force X distance)
To calculate Work output
Wout = Fr X dr
(Wout = resistance force x distance)

6. Work output can never be greater than Work input
Work output can never be greater than Work input. It will always be a smaller number than Work input.

7. Ideal machine- machine in which work input equals work output.
W in = W out
(Fe X de) = (Fr X dr)

8. Mechanical Advantage (MA)- the number of times a machine multiplies the effort force.
The higher the MA, the easier it is on you.

9. To calculate the mechanical advantage of any machine.
Variable Ending Units
Effort force (Fe) Newton
Resistance force (Fr) Newton
Mechanical Advantage None
(MA)

10. MA = Fr / Fe
Fr = MA x Fe
Fe = Fr / MA Fr . . MA Fe x

11. To find the mechanical advantage of a lever.
MA = Length of effort arm / length of resistance arm
MA = Le / Lr
MA= 30m/10m
MA= 3

12. To find the mechanical advantage of a wheel and axle
MA = radius of wheel / radius of axle
MA = 5 / 1
MA = 5

13. To find the mechanical advantage of an inclined plane
MA = Length of slope / Height of slope

14. To find the mechanical advantage of a pulley
MA = Number of pulleys you see
MA=1 MA=5 MA=4 MA=2