Physics Notes

Force- Push or pull one body exerts on another

Inertia- a body resists any change in velocity, still wants to remain still,

moving wants to remain moving, more mass greater inertia

Friction- a force that opposes motion, caused when two objects are

touching

Air Resistance- force of air against a moving object

Newton’s 1st Law- object remains at rest unless a force acts on it. Object

continues in motion in a line unless a force stops it or causes it to change direction (Inertia)

Terminal Velocity- the greatest velocity reached by a falling object

Gravity- force Earth exerts on all objects on or near it

acceleration due to gravity 9.8 m/sec²

Simple Machines Notes

Simple machines- machine that only has one part –6 types-

make work easier by increasing the amount of force you can exert

1. aid in the conservations of energy from one form to another

2. increase the force applied but not the energy

3. work done by the machine = work put into the machine

a. Work _in = work _out

Resistance force- force exerted by the machine

Effort force- force you apply to the machine

Mechanical Advantage- number of times a machine multiplies an effort force (no label)

MA= resistance force F_r ¸ effort force F_e or

resistance arm¸effort arm

Lever- changes direction or amount of force, bar that is free to pivot about a fixed point (screw driver on paint can)

Parts:

Fulcrum- point at which a lever pivots (edge of can)

Effort arm- end of lever where force is applied (handle)

Resistance arm- exerts force on object to do work (head used to pry up lid)

Types of levers:

First Class- fulcrum in middle, resistance on one end, effort on other (oar attached to boat, nail clippers, balance scale)

Second Class- Fulcrum on one end, effort on the other, resistance in middle (nutcracker, wheelbarrow, garlic press, door)

Third Class- fulcrum on one end, effort in middle, resistance on other end. (crane, drawbridge, pitcher’s arm, tweezers, stapler remover)

Inclined plane- changes the amount of force, slanted surfaced used to raise objects (ramps)

Screw- changes amount of force, inclined plane wound around a cylinder (faucets, cork screw, spiral staircase, spiral slide, cap on pop bottle)

Wedge- changes amount of force, inclined plane with one or two sloping sides. (Knife blade, nails, zipper, saws, razor, nose of boat, teeth, doorstop)

Pulley- changes amount or direction of force, (flagpole, elevator)

Wheel and axle- changes amount of force, large wheel fixed to smaller called axle & they move together (pencil sharpener, door knob, screw driver, gears)

Compound machine- more than one part

Bicycle- wheel & axle, lever

wrench- screw and lever