Newton’s Second Law

ObjectiveObjective

► At the end of today, you will be able At the end of today, you will be able to explain:to explain:

The greater the force exerted on the The greater the force exerted on the object, the greater the acceleration. object, the greater the acceleration.

For any force, the greater the mass of an For any force, the greater the mass of an object, the smaller the acceleration.object, the smaller the acceleration.► And the smaller the mass, the larger the And the smaller the mass, the larger the

acceleration. acceleration.

Newton’s Second LawNewton’s Second Law

Newton's 2nd Law Animation

Newton’s 2Newton’s 2ndnd Law Law

►Shopping Cart Simulation-Shopping Cart Simulation- What happens when more force is What happens when more force is

added to an object with the same added to an object with the same mass?mass?

What happens to the acceleration What happens to the acceleration when the same force is applied to a when the same force is applied to a larger mass? larger mass?

What is the relationship What is the relationship between force and between force and

acceleration?acceleration?► The harder you push or The harder you push or

pull something, the pull something, the faster it will accelerate.faster it will accelerate.

► Force and acceleration Force and acceleration are are directly directly proportionalproportional..

This means whatever This means whatever happens to one quantity happens to one quantity happens to the other.happens to the other.

What is the relationship What is the relationship between mass and between mass and

acceleration?acceleration?►As the As the MassMass

goes up goes up►

► TheThe AccelerationAcceleration goes downgoes down

What is the relationship What is the relationship between mass and between mass and

acceleration?acceleration?►Mass and Mass and

acceleration are acceleration are inversely inversely proportional.proportional.

►

► That means if one That means if one increases, the other increases, the other decreases.decreases.

Zero Net ForceZero Net Force► If there is zero net force, then a = 0.If there is zero net force, then a = 0.

F = maF = ma

►However, an object can be moving However, an object can be moving even if there is zero net force on the even if there is zero net force on the object.object. It is moving with a It is moving with a constant velocityconstant velocity

►Constant speed and constant direction Constant speed and constant direction (straight line)(straight line)

►Velocity remains the same if there is no Velocity remains the same if there is no acceleration.acceleration.

How does this picture How does this picture demonstrate Newton’s 2nd demonstrate Newton’s 2nd

Law?Law?

Exit TicketExit Ticket

► Johnny and Peggy Sue are each going Johnny and Peggy Sue are each going to push a 25 kg weight plate. Johnny is to push a 25 kg weight plate. Johnny is going to apply a force of 50 N, and going to apply a force of 50 N, and Peggy Sue is going to apply a force of Peggy Sue is going to apply a force of 100 N. What is each person’s 100 N. What is each person’s acceleration? Is there a difference acceleration? Is there a difference between their accelerations? If so, between their accelerations? If so, explain why they are different.explain why they are different.

►Remember: a=F / mRemember: a=F / m