Second Law of Motion Newton’s Second Law Mrs. Gergel

Newton’s Second Law of Motion The acceleration of an object depends on the mass of the object and the amount of force applied This law describes the motion of an object when an unbalanced force acts on the object

Part 1: Acceleration depends on mass The acceleration of an object decreases as its mass increases The acceleration of an object increases as its mass decreases Acceleration Acceleration

Part 2: Acceleration depends on force An object’s acceleration increases as the force on the object increases An object’s acceleration decreases as the force on an object decreases The acceleration of an object is always in the same direction as the force applied Acceleration Acceleration

This law explains why objects fall to earth with the same acceleration They both have the same acceleration (gravity) That means the one with more mass will have more force when it hits the ground. Which will have more force, the elephant or the hockey puck?

Activity You will be using the ramps and the cars from Newton’s First Law activity. Take the mass of both of your cars Run them down the ramp 5 times each and calculate their average speed. Answer your two conclusion questions.

Newton’s 2nd Law: Formula We can express Newton’s Second Law mathematically F=M x A or A=M/F A= acceleration, M=mass, F= net force

F = MA F ÷ ÷ M x A Force = mass X acceleration

2nd Law Vocabulary: Force = a push or a pull Mass = the amount of matter in an object Your weight changes on the moon. Does your mass change also? Acceleration = a change in velocity Name some changes in velocity a car could make that would mean it is accelerating?

What does F = ma say? F = ma basically means that the force of an object comes from its mass and its acceleration. Something very massive (high mass) that’s changing speed very slowly (low acceleration), like a glacier, can still have great force. Something very small (low mass) that’s changing speed very quickly (high acceleration), like a bullet, can still have a great force. Something very small changing speed very slowly will have a very weak force.

             Newton's Laws of Motion Newton’s Second Law:  

F=MA A truck that weights 2500 kg accelerates at a rate of 5 m/s². What is the net force?

F=MA A truck that weights 2500 kg accelerates at a rate of 5 m/s². What is the net force? 12500 N

F=MA How much force is required to accelerate a 2 kg mass at 3 m/s²?

F=MA How much force is required to accelerate a 2 kg mass at 3 m/s²? 6 N

M=F/A A sumo wrestler is accelerating at a rate of 3 m/s² with a net force of 600 N. what is the mass of the sumo wrestler?

M=F/A A sumo wrestler is accelerating at a rate of 3 m/s² with a net force of 600 N. what is the mass of the sumo wrestler? 200 Kg

M=F/A Given a force of 56 N and a n acceleration of 7 m/s², what is the mass?

M=F/A Given a force of 56 N and a n acceleration of 7 m/s², what is the mass? 8 kg

A=F/M A runner has a force of 150 N and a mass of 75 kg. what is the runner’s acceleration?

A=F/M A runner has a force of 150 N and a mass of 75 kg. what is the runner’s acceleration? 2 m/s²

A=F/M What is the acceleration of an object that weights 10 kg and a force of 60 N?

A=F/M What is the acceleration of an object that weights 10 kg and a force of 60 N? 6 m/s²

Practice Problems Given a force of 88 N and an acceleration of 4 m/s², what is the mass? How much force is required to accelerate a 5kg mass at 20 m/s? What is the acceleration of a 24 kg mass pushed by a 6 N force?

Practice Problems Given a force of 88 N and an acceleration of 4 m/s², what is the mass? 22kg How much force is required to accelerate a 5kg mass at 20 m/s? 100 N What is the acceleration of a 24 kg mass pushed by a 6 N force? 0.25 m/s²