Without friction…..Without friction…..a.There would be no need for machines

b. Input work would be greater than output work

c. Actual mechanical advantage would equal the ideal mechanical advantage

d.Output work would equal input work

Which of the following are Which of the following are examples of a first class lever?examples of a first class lever?

Which of the following are Which of the following are examples of a second class lever?examples of a second class lever?

Which of the following are Which of the following are examples of a third class lever?examples of a third class lever?

Simple machine?

Wedges

What about these teeth?

Fulcrum?

How is this picture related to How is this picture related to simple machines?simple machines?

Where’s the fulcrum?

Where’s the load?

Where’s the effort?

What is the mechanical What is the mechanical advantage of a machine if the advantage of a machine if the output force is 100 N and the output force is 100 N and the

input force is 25N?input force is 25N?

Output force divided by input force = 4

This rope and pulley This rope and pulley system supports thesystem supports the

400 lb weight. 400 lb weight. How much tension How much tension

in the rope is needed in the rope is needed

to hold the weight into hold the weight in equilibrium? equilibrium?

400------- = 100 4

What is the mechanical advantage of What is the mechanical advantage of this simple machine if the diameter this simple machine if the diameter

of the wheel is 24 inches and the of the wheel is 24 inches and the radius of the axle is 2 inches?radius of the axle is 2 inches?

12------- = 6 2

In a screw, which is In a screw, which is greater….the input force or greater….the input force or

output force?output force?

When using a baseball bat, which is When using a baseball bat, which is greater….the input force or output greater….the input force or output

force?force?

If the input arm is 5 cm long and the If the input arm is 5 cm long and the output arm is 1 cm long, what is the output arm is 1 cm long, what is the mechanical advantage of the lever?mechanical advantage of the lever?

5

With a mechanical advantage of With a mechanical advantage of 5, how much effort is needed to 5, how much effort is needed to

lift a 500 N load? lift a 500 N load?

100

If the load is moved closer to the If the load is moved closer to the fulcrum, will the input force required fulcrum, will the input force required to lift the load increase or decrease?to lift the load increase or decrease?

If D1 is 2 meters and D2 is 8 meters, what is the If D1 is 2 meters and D2 is 8 meters, what is the length of the resistance arm? length of the resistance arm?

10

What is the length of the effort armWhat is the length of the effort arm? ?

2

Mechanical advantageMechanical advantage? ?

0.2

Which way would I need to Which way would I need to move the load to decrease the move the load to decrease the

amount of input force needed to amount of input force needed to move the load?move the load?

If the distance from the truck bed to the If the distance from the truck bed to the ground is 2 meters and the ramp’s length is ground is 2 meters and the ramp’s length is

10 meters, what is the mechanical 10 meters, what is the mechanical advantage?advantage?

5

Which lever arrangement requires the least Which lever arrangement requires the least effort force to raise a 500 N resistance? effort force to raise a 500 N resistance?

0

20 40 60 80 100

100

200

300

400

500

Ramp 1

Ramp 2Ramp 3

Input Force (n)

Ou

tpu

t F

orc

e (

n)

Mechanical Advantage of Ramps