MOTION & FORCESCH. 10-11

d. motion: an object’s change in position relative to a reference point

What is motion?

How do you know the balloon moved?

Distance measures the actual path an object travels.Displacement measures the from start to finish in a straight line.

Displacement

d. speed: distance traveled in a certain amount of time

SI unit: meter/second (m/s)d. velocity: speed of an object in a certain direction

examples?d. acceleration: any change in velocity (speed, direction, or both)

SI unit: meter/second2 (m/s2)

A car slows down to stop at a stop light.

Which is which?

A plane travels at 300 mph towards California.

A cheetah runs 30 mph.

A car turns left at an intersection.

acceleration

velocity

speed

acceleration

d. force: an action exerted on an object to change the object’s state of rest or motion

•has direction & magnitude•What is another term for “state of rest or motion?”•INERTIA!

What is force?

FORCES

FORCES

d. friction: a force that opposes motion between two surfaces that are in contact

•What is the difference between static and kinetic friction?

What is friction?

All objects in the universe attract each other through gravitational force.

Gravity

Sir Isaac Newton, 1642-1727

Gravity increases asmass increases.

Gravity decreases as distance increases.

An object at rest tends to remain at rest and an object in motion tends to stay in motion unless acted upon by an outside force.

Newton’s 1st Law

The unbalanced force acting on an object equals the object’s mass times its acceleration.

F = ma

Newton’s 2nd Law

For every action, there is an equal & opposite reaction.• Force always happens in

pairs, even when there is no motion.

Newton’s 3rd Law

When A swimmer pushes the water back, which way does she go?When you push down on the floor, which way do you go?

Newton’s 3rd Law