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47 Cards in this Set
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Inertia

tendency of an object to resist a change in motion
Inertia depends on the objects mass. More Mass=More Inertia=Harder to Start/Stop Less Mass=Less Inertia=Easier to Start/Stop 

Newton's First Law

An object at rest will stay at rest and an object in motion will stay in motion until acted on by an unbalanced force.


Force

push or pull that can cause an object accelerate
Unitskgm/s2 Force is a vector quantity 

Net Force

combination of all forces that act on an object
Symbol<sum>F 

Unbalanced Force

An unequal force that changes an objects motion
(<sum>F!=0) 

Balanced Force

Equal forces acting on an object in opposite directions, will not cause a change in motion. (<sum>F=0)


Two Types of Balanced Forces

Static/Mechanical Equilibrium: objects at rest (<sum>F=0)
Normal Force/Support Force Dynamic Equilibrium: object moving at constant velocity (<sum>F=00 Moving Force=Resisting Force 

Newton's Second Law

Force=Mass x Acceleration
Mass and acceleration are inversely proportional Force and acceleration are directly proportional 

Newton's Third Law

For every action there is an equal but opposite reaction


Why dont action and reaction forces cancel each other out as a balanced force?

Forces are added together to get a balanced force only if the force is acting on the same object. Action and reaction forces are applied to different objects.


Motion

An object is considered in motion when its distance from another object changes


Reference Point

Object or place used for comparison to determine if an object is in motion


Speed

Distance object travels in time
Speed=Distance/Time 

Velocity

Speed in a given direction


Acceleration

Rate at which the velocity changes
(Final VelocityInitial Velocity)/Time 

3 types of acceleration

Increase (positive)
Decrease (negative) Change Direction (centripetal acceleration) 

Aristotle

384322 BC
Studied under Plato Philosopher and scientist Tutor to Alexander The Great One of first to look at physical world of science Started school called Lyceum Natural Motionobjects natural state is rest Unnatural Motionforce required causing motion Heavier objects fall faster than lighter objects Based work on observation and logic 

Galileo

Late 1500searly 1600s
Went to University of Pisa Dropped out which allowed him time to research physics Started experiments with motion Was a teacher at colleges Became advocate of Copernicus In 1609 was first to use telescope In 1630s wrote a book called Dialogue Went to jail Went blind because he looked at the sun too much Once an object is in motion no force is needed to keep it in motion Force needed to change the motion of an object Inertiatendency of an object to resist a change in motion All object fall at the same rate Based work on experimentation 

Projectile Motion

An object upon which the only force acting on it is gravity


Types of Projectiles

An object dropped from rest
An object which is thrown vertically upwards An object is which thrown upwards at an angle is also a projectile 

what are the velocities of projectiles?

Highest velocity when released
As objects travel upward gravity slows object to 0 As object travels downward gravity increases velocity Highest velocity when object hits ground 

What are the components of a projectile?

The path of a projectile has a horizontal component and a vertical component.
They are independent of each other The projectile moves forward because of inertia The projectile accelerates downward because of gravity 

Work

Work is done on an object when a force is exerted on an object that causes the object to move some distance


What two things must be controlled in order for work to be done?

No work without motion
No work without force in the same direction 

Formula for work

Work=ForceDistance


Power

The rate at which work is done


Formula for power

Power=Work/Time


What 3 things do machines do to make work easier?

Change the amount of force you input
Change the distance over which you exert the force Change the direction of the way you apply force 

Why doesn't the total work change?

If a machine allows you to apply a smaller force the distance will increase
If a machine reduces the distance the force will increase If a machine allows you to apply a force in a different direction it doesnt change how much force you have to apply or how far you move it 

What is the mechanical advantage?

The number of times a force exerted on a machine is multiplied by the machine


Formula for mechanical advantage

M.A.=Output Force÷Input Force


What happens if M.A.>1?

If M.A.>1 machine multiplies the input force


What happens if M.A.<1?

If M.A.<1 machine multiplies the input distance


What happens if M.A.=1?

If M.A.=1 changing direction


Efficiency

Compares output work to input work (%)


Formula for efficiency

Efficiency=Output work÷Input Work100


Can efficiency be greater or equal to 100?

No


Friction

the resistive force that opposes motion or attempted motion of an object past another with which it is in contact or through a fluid


What 2 factors does friction depend on?

Kinds of Surfaces
Pressure Between Surfaces Surface Area DOES NOT Affect Friction 

3 types of friction

Sliding
Fluid Rolling 

Gravity

a force that pulls objects towards the earth


Rate of acceleration

9.81 m/s


Terminal velocity

highest velocity that an object reaches


Mass

quantity of matter in an object


Weight

the gravitational force exerted on an object by the nearest most massive object


Universal law of gravitation formula

F(grav.)=Gmsub1msub2/dsquared


What are the 6 simple machines?

Lever
Pulley Inclined Plane Wheel & Axel Wedge Screw 