Newton’s Second Newton’s Second LawLaw

Chapter 3 Section 1

Newton’s Second LawNewton’s Second LawSuppose you are stuck in the Suppose you are stuck in the

mud with your carmud with your carWould you rather have a Would you rather have a

Corvette or a Conversion van?Corvette or a Conversion van?Would you rather be as strong Would you rather be as strong

as you or the weight lifting as you or the weight lifting champion?champion?

Both force and mass are Both force and mass are important in your decisionimportant in your decision

If you apply 10 N of force to a If you apply 10 N of force to a 5 kg object and that same 10 N 5 kg object and that same 10 N of force to a 50 kg object, of force to a 50 kg object, which would have more which would have more motion?motion?

If you apply 10 N to a 5 kg If you apply 10 N to a 5 kg object and 20 N to the same object and 20 N to the same object, which would increase in object, which would increase in motion more?motion more?

Newton’s second law includes Newton’s second law includes both mass & forceboth mass & force

Newton’s Second LawNewton’s Second Law states states that a net force acting on an that a net force acting on an object causes the object to object causes the object to accelerate. The size of accelerate. The size of acceleration depends directly on acceleration depends directly on the force applied and indirectly the force applied and indirectly on the mass of the object.on the mass of the object.

Force = mass x accelerationForce = mass x acceleration

Force = mass x accelerationForce = mass x accelerationF = maF = ma

–Mass in kilogramsMass in kilograms

–acceleration in m/sacceleration in m/s22

–force in Newtonsforce in Newtons»Newton = kilogram * m/sNewton = kilogram * m/s22

FrictionFrictionThe force that opposes motionThe force that opposes motion

–two surfaces in contacttwo surfaces in contact

–air resistanceair resistanceWhy would friction be bad?Why would friction be bad?Why would friction be good?Why would friction be good?

Types of FrictionTypes of Friction Static FrictionStatic Friction is the frictional force that is the frictional force that

prevents the objects from sliding on each prevents the objects from sliding on each otherother

Sliding FrictionSliding Friction is the frictional force that is the frictional force that opposes the motion of moving objectsopposes the motion of moving objects

Rolling FrictionRolling Friction is the frictional force is the frictional force between a rolling object and the surface it between a rolling object and the surface it rolls on rolls on

Falling ObjectsFalling ObjectsNewton’s second law applies to Newton’s second law applies to

falling objects alsofalling objects alsoº a = 9.8 m/sa = 9.8 m/s22

If you are on the surface of the If you are on the surface of the earth your weight would be earth your weight would be your mass times 9.8 m/syour mass times 9.8 m/s22

Air resistanceAir resistanceThe force acting in the opposite The force acting in the opposite

direction because of the direction because of the atmosphere. atmosphere.

Acts on moving objects onlyActs on moving objects onlyActs in the opposite direction of Acts in the opposite direction of

motionmotion

Terminal velocityTerminal velocityThe highest velocity that can be The highest velocity that can be

reachedreachedwhen force moving object when force moving object

forward (down) equals the force forward (down) equals the force of friction (air resistance)of friction (air resistance)