Forces #1 - Newton's Laws of Motion (Verhoeve)

What is a force?

Anything that pushes or pulls an object. It has a direction, so its a vector.

Forces are measured in:

Newtons (N)

What is a Net Force? (Fnet)

The vector sum of all the forces acting on an object. After opposing forces cancel out, this is the amount/direction left over.

What forces are acting on an apple hanging from a tree?

Gravity (down), applied force (up)

What forces are acting on pushing a cart on a road?

The pushing / applied force, friction

Newton's 1st Law of Motion

An object at rest will stay at rest and an object in motion will stay in motion, at constant velocity, unless acted on by an external net force.

What is intertia?

The resistance an object has to change its state of motion.

What will a non-zero net force do?

It will change the velocity of the object in magnitude, direction, or both.

A net force is not required to maintain the ___________ of an object.

Velocity.

External force

a force between a part of a system and something outside the system

Internal force

exerted by one part of a system on another

In Newton's 1st law of motion, what is the acceleration?

0

Newton's 2nd Law of Motion

the acceleration of an object will be directly proportional to the net force acting on the object and inversely proportional to the mass of the object. The object will accelerate in the direction of the net force

What equation is used for Newton's 2nd Law of Motion?

Fnet = ma

1 N =

1 kg·m/s^2

Newton's 3rd Law of Motion

For every action force, there is an equal and opposite reaction force

Equal in magnitude…

…opposite in direction

How to write 3rd law as an equation?

F a on b = -F b on a