Newton’s Second Law Chapter 3 Section 1

Newton’s Second Law Suppose you are stuck in the mud with your car Suppose you are stuck in the mud with your car Would you rather have a Corvette or a Conversion van? Would you rather have a Corvette or a Conversion van? Would you rather be as strong as you or the weight lifting champion? Would you rather be as strong as you or the weight lifting champion?

Both force and mass are important in your decision Both force and mass are important in your decision If you apply 10 N of force to a 5 kg object and that same 10 N of force to a 50 kg object, which would have more motion? If you apply 10 N of force to a 5 kg object and that same 10 N of force to a 50 kg object, which would have more motion?

If you apply 10 N to a 5 kg object and 20 N to the same object, which would increase in motion more? If you apply 10 N to a 5 kg object and 20 N to the same object, which would increase in motion more? Newton’s second law includes both mass & force Newton’s second law includes both mass & force

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

F = ma F = ma –Mass in kilograms –acceleration in m/s 2 –force in Newtons »Newton = kilogram * m/s 2

Friction The force that opposes motion The force that opposes motion –two surfaces in contact –air resistance Why would friction be bad? Why would friction be bad? Why would friction be good? Why would friction be good?

Types of Friction Static Friction is the frictional force that prevents the objects from sliding on each other Static Friction is the frictional force that prevents the objects from sliding on each other Sliding Friction is the frictional force that opposes the motion of moving objects Sliding Friction is the frictional force that opposes the motion of moving objects Rolling Friction is the frictional force between a rolling object and the surface it rolls on Rolling Friction is the frictional force between a rolling object and the surface it rolls on

Falling Objects Newton’s second law applies to falling objects also Newton’s second law applies to falling objects also ºa = 9.8 m/s 2 If you are on the surface of the earth your weight would be your mass times 9.8 m/s 2 If you are on the surface of the earth your weight would be your mass times 9.8 m/s 2

Air resistance The force acting in the opposite direction because of the atmosphere. The force acting in the opposite direction because of the atmosphere. Acts on moving objects only Acts on moving objects only Acts in the opposite direction of motion Acts in the opposite direction of motion

Terminal velocity The highest velocity that can be reached The highest velocity that can be reached when force moving object forward (down) equals the force of friction (air resistance) when force moving object forward (down) equals the force of friction (air resistance)