prepwalk

1. PHYSICS
MACHINES
Short revision series

2. Understanding mechanical
advantage and velocity ratio
 M.A = Ratio of load to the effort = L/E
 V.R = Ratio of distance moved by the effort to
the distance moved by the load
= distance moved by E = x E
distance moved by L x L
 Efficiency =M.A/V.R x 100%
= work output x 100%
work input

3. Common simple machines
1. LEVER : Has fulcrum, effort, load.
 FIRST ORDER eg claw hammer, crowbar,
pliers
 M.A = V.R

4.  SECOND ORDER eg nutcracker,
wheelbarrow. L is between F and E.

5.  THIRD ORDER E is between L and F. Eg
forearm, Tongs

6. 2 Pulley
 In a simple pulley when there is no friction
L = T = E
M.A = 1 = V.R
3 Inclined plane
V.R = x E/x L
= AB/BC = x/h
VR = 1/sinθ
B
CA
hx
θ

7.  Screw
 V.R = 2πa/pitch(p)