1. Simple Machines: The Wheel & Axle

2. Wheel & Axle part of the lever family
simple machine made of a large wheel secured to a smaller wheel called an axle.
larger wheel (or outside) rotates around the smaller wheel (axle)
a lever that rotates in a circle around a center point or fulcrum
Can move object further than with a lever

3. Wheel & Axle wheel and axle is a modification of a lever.
wheel is fixed shaft.
wheel & shaft must work together to = simple machine.
Sometimes wheel has crank or handle
is a lever that rotates in a circle around a center point or fulcrum.
The larger wheel (or outside) rotates around the smaller wheel (axle).

4. Examples doorknob roller skates carts skateboards bikes cars casters
rotary dial phone
egg beater
windmill
bike
fan
rolling pen
wagon
pencil sharpener
Pics at

5. Old Fashioned Eggbeater

6. Pencil Sharpener http://www.inmagine.com/kcd00024/kcd00024092-photo

7. Rotary Phone http://www.cartoonstock.com/lowres/dco0018l.jpg

8. Mechanical Advantage MA > 1 Formulas Machine magnifies input force
Distance travelled is increased
Formulas
IMA = Radius of wheel .
Radius of axle OR
IMA = Fo Fi

9. Video Clips http://www.youtube.com/watch?v=qlI9GlUUlbg
Tim and Moby -
Eureka Screw & Wheel -
Eureka – Mechanical Advantage -

10. Example #1
This is Ms. Tedrow’s cool ride If the radius of the the hot rod’s axle is 5 cm and the radius of the tire is 25 cm, then what is the mechanical advantage?

11. Answer #1
MA = 5

12. Example #2
Have you remember this rad ride? Yup, you guessed it! It is Ms. Logan’s ride!!! Yay! If the mechanical advantage of her wheel & axle is 5 and the radius of the tire is 60 cm, then what is the radius of the axle?

13. Answer #2
12 cm

14. Example #3
WOW-EEEEEEE! Yikes, this is one mad monster truck! If the diameter of the tire is 60 cm and the circumference of the axle is cm, then what is the mechanical advantage of the wheel and axle?

15. Answer #3
MA = 15

16. Example #4
The power steering in an automobile has a mechanical advantage of roughly 75. If the input force on the steering wheel is 10 N, what is the output force that turns the car’s front wheels?

17. Answer #4
750 N