Force, Motion, Simple Machines and Waves

Most Important Info

Newton’s Laws

1. An object in motion stays in motion; an object at rest stays at rest UNLESS force acts on it

2. Acceleration of an object depends on its mass and the force applied to it (the heavier something is, the more force it needs to move)

3. Every action has an equal and opposite reaction

Measurements

• Force measured in Newtons (N)• Work measured in Joules (J)• Power measured in watts (W)

Work

• Work is being done on an object when the direction of force and direction of movement are the same

• The object MUST MOVE or work hasn’t been done

• Work = force x distance

Power

• How fast you do work

• P = Work/Time

• How much power does a machine have if it does 50J of work in 2 min?

Simple Machines

1. Lever: a bar that pivots on a fulcrum ex) hammer, arm, see saw, wheelbarrow

2. Pulley: grooved wheel that holds a rope (fixed or moveable) ex) flagpole

3. Wheel and Axle: a circular wheel that spins around on an axis ex) car, doorknob, any wheel on anything

Simple Machines

4. Inclines Plane: straight, slanted surface to help raise a load ex) ramp

5. Wedge: 2 inclines planes together used to cut ex) knife, ax,

6. Screw: an inclined plane that is wrapped around in a spiral used to hold things together

Compound Machine

• 2 or more simple machines put together• Ex) can opener (wheel and axle, wedge, lever)

Types of Waves

1. Transverse: (moves Perpendicular)

2. Longitudinal: (moves parallel)

Types of waves

• Electromagnetic: transverse wave that does NOT need a medium

• Mechanical: needs a medium (seismic waves travel through the earth to cause an earthquake)

Objects in a wave

• Move UP and DOWN

Parts of a wave

1. Crest: (top)2. Trough (bottom)3. Amplitude (middle to the top)4. Wavelength (crest to crest)

Frequency and Wavelength

• Are opposites! • Frequency= how fast the waves are moving• Wavelength= distance between waves

• As frequency increase, wavelength decreases• The faster the waves are moving, the less

distance is between them