ACCELERATE D MOTION NEWTONS SECOND LAW OF MOTION

ACCELERATE D MOTION

NEWTON’S SECOND LAW OF MOTION • States the relationship between: – mass – force – acceleration

A net force acting on an object; • causes the object to accelerate • in the same direction of the force

The amount of acceleration is determined by 2 things!

1. ) the size of the force • larger force causes greater acceleration – (force is directly proportional to acceleration)

2. ) the mass of the object • larger mass results in less acceleration – (mass is inversely proportional to acceleration)

NEWTON’S 2 nd law Equation • force = mass x acceleration F = ma

UNITS of FORCE

Mass • is measured in kilograms (kg)

Acceleration • is measured in meters per second per 2 second (m/s )

Force • is measured in Newtons (N)

Knowing that…. . • force = mass x acceleration *THEN* • 1 Newton must equal 1 kg • m/s 2

If you drop a bowling ball and a marble from a bridge at the same time which will hit the ground first?

The bowling ball and the marble will hit the ground; • at the same time • Why?

Even though the bowling ball has more mass than the marble, • it also has more inertia (resistance to a force)

Acceleration caused by Earth’s gravity. 2 (g) = 9. 8 m/s

Objects that are pushed or thrown downward • are accelerated by two forces: 1. ) the force of gravity 2. ) the force of the “push or throw”

Objects that are pushed or thrown downward • have an acceleration greater than 9. 8 m/s 2

Since Freely Falling objects dropped at the same time should reach the ground at the same time…. .

Why does a penny dropped at the same time as a feather, land on the ground first?

Air Resistance: • force that air exerts on all moving objects • goes against an object’s motion car’s motion air resistance

As gravity pulls an object down; • Air resistance pushes up

Air Resistance depends upon 3 things. 1. ) velocity 2. ) shape 3. ) density

The longer an object is allowed to fall; • the air resistance increases upward

Terminal Velocity • Highest velocity that will be reached by a falling object