1. SPH4C – Unit #2 Mechanical Systems
Simple Machines
SPH4C – Unit #2 Mechanical Systems

2. Learning goals and success criteria
Today I will…
Define a machine
Distinguish between various simple machines such as the pulley and lever families of machines

3. Simple Machines
Although many modern machines are large and complex, they usually operate on the basic principles of simple machines, principles that have been used for centuries. For example:
In museums, we often see early tools and weapons whose sharp edges are examples of a simple machine. The wedge at the end of a spear applies a large force to split the hide of a deer or other food source.

4. Simple Machines
Although many modern machines are large and complex, they usually operate on the basic principles of simple machines, principles that have been used for centuries. For example:
The early Egyptians used ramps to move blocks when building pyramids; ramps are also an example of a simple machine. The inclined plane reduces the force needed to move a stone block to a higher level.

5. Simple Machines
Although many modern machines are large and complex, they usually operate on the basic principles of simple machines, principles that have been used for centuries. For example:
Even today, the ancient technology of pulleys and levers is often used to raise water out of rivers and wells.

6. Simple Machines
A machine is a device that helps us perform tasks. It is designed to achieve at least one of five main functions.
Change energy from one form into another (i.e. a hydroelectric generator changes the energy of falling water into electrical energy);

7. Simple Machines
A machine is a device that helps us perform tasks. It is designed to achieve at least one of five main functions.
Transfer forces (i.e. a car transmission transfers the force from the motor to the wheels);

8. Simple Machines
A machine is a device that helps us perform tasks. It is designed to achieve at least one of five main functions.
Change the direction of a force (i.e. to raise a flag up a pole, we pull down on a rope attached to a pulley at the top of the pole);

9. Simple Machines
A machine is a device that helps us perform tasks. It is designed to achieve at least one of five main functions.
Change the magnitude of a force (i.e. a system of pulleys helps a mechanic exert a small force to hoist a heavy engine out of a car);

10. Simple Machines
A machine is a device that helps us perform tasks. It is designed to achieve at least one of five main functions.
Change the distance or speed (i.e. the outer circumference of the rear wheel of a bicycle moves farther and faster than the circumference of the sprocket wheel attached to the pedals).

11. Simple Machines
Note: Simple machines can be split into two families that share characteristics: the lever family of machines and the inclined family of machines. The lever family consists of the lever, the pulley, the wheel and axle, and gears. The inclined family consists of the inclined plane, the wedge, and the screw.

12. Simple Machines Machine
Device that helps us perform tasks by performing one or more of five main functions.
2 families:
Lever family
Lever, pulley, wheel and axle, gears
Inclined family
Inclined plane, wedge, screw

13. Simple Machines Practice Axe Tennis racket Doorknob Screwdriver
State the main function of each of the following:
Axe
Tennis racket
Doorknob
Screwdriver
(a) wedge
(b) lever
(c) Wheel and axle
(d) screw

14. Homework
Read: Pg