October 13

In class today we went over some notes that relate to Newton's Law Lab Part 2:

Newton's 3rd Law- If Object A exerts a force on Object B then Object B exerts a force on Object A

The 2 forces must...

1) act on different objects

2) be equal in size

3) be opposite in direction

4) be the same type of force (grav, normal...)

Newton's 1st Law- Objects want to keep their previous velocity (inertia.) If an objects velocity is constant the net force=0

This relates to #11 on the lab. We are trying to figure out that Force A (the contact force of the cart on the spring scale) is equal to Force C (the contact force of the air on the cart.) Force B is the contact force of the spring scale on the cart.

a=b; Relates to Newton's 3rd law because the forces are opposite. The contact force of cart on the spring scale and the contact force of the spring scale on the cart, by Newton's 3rd law, are always equal. Because of Newton's third law, this is always true.

b=c; Relates to Newton's 1st Law because the velocity is constant. The net force of Force B+Force C=0.

Because of the transitive property, if a=b and b=c, then a=c.

How do we find acceleration?

In a velocity vs. time graph the slope represents acceleration (a=change in v/change in t)

How do we find net force?

The force of gravity and the normal force cancel each other out, so in this instance we measure the force of air on the cart