Newton’s Laws

Newton’s First Law

• An object moving at a constant velocity keeps moving at that velocity unless acted upon by an unbalanced net force

Newton’s First Law Continued…

• An object at rest remains at rest unless acted upon by an unbalanced net force

• How does a seatbelt relate to Newton’s First Law?

• http://www.youtube.com/watch?v=4NQbeZ0EXZQ&list=PL0CDAF675CAEE090B&index=8

Newton’s Second Law

• The acceleration of an object is in the same direction as the net force on the object

Force• Force = Mass x Acceleration• F=ma• Force is measured in Newtons (N)• You push a friend sitting on a swing. She has

a mass of 50 kg and accelerates at a rate of 4 m/s2. Find the force you exerted.

F = 50kg x 4 m/s2 =

F = 200 N

Force Videos• FSN Force - http://www.youtube.com/watch?v=A_wnt84iyMk

• NFL Impact - http://www.wired.com/wiredscience/2010/11/espn-sport-science-on-collisions-video-break-down

Centripetal Force• The net force exerted toward

the center of a curved path

• Ex: Bucket of Water,

Earth and Moon

• http://www.youtube.com/watch?v=bWiVv--OTYA

Newton’s Third Law• “To every action force there is

an equal and opposite reaction force”

Action and Reaction• For every action there is an

equal and opposite reaction.

Action and Reaction Forces Don’t Cancel

Momentum• Related to how much force is

needed to change its motion

p=mvp momentum (kg∙m/s)

m mass (kg)

v velocity (m/s)

Law of Conservation of Momentum

• The momentum of an object doesn’t change unless its mass, velocity, or both change

• Bill Nye - Momentum

– http://www.youtube.com/watch?v=y2Gb4NIv0Xg