Lecture 11: Laws of motion. Newton’s 1 st Law: Inertia Matter resists motion If at rest, it will stay at rest If in motion, it will stay in motion Mass.

Lecture 11: Laws of motionLecture 11: Laws of motion

Newton’s 1Newton’s 1stst Law: Inertia Law: Inertia

Matter resists Matter resists motionmotion

If at rest, it will stay If at rest, it will stay at restat rest

If in motion, it will If in motion, it will stay in motionstay in motion

Mass is a Mass is a measure measure of of inertiainertia

Newton’s 2Newton’s 2ndnd Law Law

An unbalanced An unbalanced force acts on force acts on objects equal to objects equal to its its mass mass and and accelerationacceleration

F = m X aF = m X a

F = forceF = force m = massm = mass a = acceleration a = acceleration

GravityGravity

All objects in the All objects in the universe attract universe attract each othereach other

Gravity is a Gravity is a function of function of mass mass and and distancedistance

More mass= More mass= more more gravitygravity

More distance = More distance = less less gravity gravity

Weight and gravityWeight and gravity

The pull of gravity on The pull of gravity on Earth is 9.8m/s Earth is 9.8m/s 22

Weight is mass X the Weight is mass X the pull of gravity (w=mg)pull of gravity (w=mg)

Q: are weight and mass Q: are weight and mass the same?the same?

Q: do we weigh the Q: do we weigh the same on the moon as same on the moon as on earth?on earth?

Terminal velocityTerminal velocity

The maximum The maximum speed objects fall speed objects fall to earth isto earth is

200 mi/h or 200 mi/h or 320km/h320km/h

How does the How does the parachute slow the parachute slow the fall?fall?

Newton’s 3Newton’s 3rdrd Law Law

Forces act in pairsForces act in pairs

For every For every actionaction force, there is an force, there is an equalequal and and opposite opposite reactionreaction force force

Momentum = mass X velocityMomentum = mass X velocity

The greater the The greater the mass, the greater mass, the greater the momentum.the momentum.

Ex: semi trucks Ex: semi trucks take longer to stop take longer to stop than cars.than cars.

Q: will momentum Q: will momentum be greater at more be greater at more velocity?velocity?

Action and reaction force pairsAction and reaction force pairs