Embedded Files
SIMPLE MACHINES.
1. Work equation=
Force X distance.
The unit is Newtons X meters = joules.
Ex. How much energy does it take to move an object 20 meters if it has a force of 300 N?
300 N X 20 meters = 6000 J
2. ** Work in = Work out
LEVER
Force X distance(effort) = Force X distance(resistance)
Ex. How much force would be needed to move an object 2 dm from the fulcrum, if you supply 4 N of force on the end of a lever that is 8 dm long?
(4N )(8 dm) =(X N)(2 dm)
(4N )(8 dm) =( X N)(2 dm)
(2 dm) (2 dm)
X= 16 N
3. Power = Work
Time
Labels = Watt= Joules
seconds
Ex. What is the power needed to move a stove in 20 seconds if you supply 2000 joules?
Power = Work = 2000 joules = 100 W
Time 20 seconds
4. Efficiency =Work out(100) = %
Work in
Ex. What is the efficiency of a motor that has 800 joules of work output, but takes in 2400 joules of electricity?
Efficiency =800 j(100) = 33.3%
2400 j
5. MA of a wheel and axle
MA(Mechanical Advantage) = rw/ ra
rw = radius of wheel
ra = radius of axle
Ex. A motorcycle has a wheel radius of 40cm. Its axle has a radius of 4 cm. What is the mechanical advantage of the motorcycle?
MA = rw/ ra
MA = 40 cm/ 4 cm = 10 T.M.E
T.M.E.=Times more efficient
6. Mechanical advantage of a lever.
MA= Fr / Fe
Fr = resistance force
Fe = effort force
Ex. A worker applies an effort force of 10 N to pry open a window that has a resistance of 40 N. What is the mechanical advantage of the crowbar?
MA= Fr / Fe
40 N / 10 N = 4 T.M.E.
7. Mechanical advantage of a lever
MA = Le / Lr
Le = length of effort arm
Lr = length of resistance arm
Ex.A worker uses an iron bar to raise a manhole cover. The effort arm is 500 cm long. The resistance arm is 100 cm long. What is the mechanical advantage of the bar?
MA = Le / Lr
MA = 500 cm / 100 cm
MA = 5 T.M.E.
8. Mechanical Advantage of a ramp
MA = length/ height
What is the mechanical advantage for a ramp that is 12 meters long, and 3 meters high?
MA = length/ height
MA = 12 m / 3 m = 4 T.M.E.
Page updated
Report abuse