MORE SIMPLE MACHINES

WHEEL AND AXLE

• What is it?• 2 circular or cylindrical objects fastened together that

rotate about a common axis

• How it works• Smaller input force applied on the wheel, exerts a larger

output force on the axle

• Increases your force, so you must exert your force over a long distance• To increase distance, exert force on the axle

IMA OF A WHEEL AND AXLE

• IMA = Radius of Wheel divided by the radius of the axle

IMA = Radius of Wheel / Radius of Axle

WRITE YOUR THOUGHTS

To increase IMA, would you increase the radius of the wheel or the axle?

PULLEY

• What is it?• A grooved wheel with a rope or cable wrapped around it

• How it works• Pull on end of the rope (Input Force), the other ends pulls

a load (Output Force)

• Pulleys can decrease input force• Pulleys can change the direction you apply force

TYPES OF PULLEYS

• Fixed Pulley = attached to a structure• Moveable Pulley = attached to a load• Block and Tackle = a combination of fixed and

moveable pulleys

IMA OF A PULLEY

• IMA = number of sections of rope that support the object or load

• What is the IMA of a fixed pulley? A moveable pulley?

SIMPLE MACHINES IN THE BODY

• Most of the machines in your body are levers• Tendons and muscles pull bones• Joints act as fulcrums

• Sharp front teeth (Incisors) act as wedges

COMPOUND MACHINES

• Many Machines consist of combinations of simple machines• Compound Machine: a machine that utilizes 2 or

more simple machines• IMA = total IMA of all machines that make up the

compound machine