1. Get ready for today… Yes, Cornell notes!
Turn in your Free Body Diagram page (did you circle Balanced / Unbalanced??).
Turn in any other homework still missing (vocab, Newton’s Laws).
Turn to the next blank page in your journal and set it up for today’s notes 
Page: 17
Date:
Title: Newton’s Second Law
Essential Question: How are force, mass, and acceleration related?
Yes, Cornell notes!

2. Today’s notes: There are three slides of notes.
There are six sets of slides posted outside the room.
You will have 10 minutes to copy the notes and come back inside.
After 10 minutes, I will go through the information quickly to be sure you understand.
If you finish early, you may begin working on today’s handout.

3. Newton’s Second Law Acceleration is DIRECTLY PROPORTIONAL to net force
they do the same thing – if one increases, the other increases…if one decreases, the other decreases
double the force means double the acceleration
Acceleration is INVERSELY PROPORTIONAL to mass
they do the opposite – if one increases, the other decreases and vice versa
double the mass means HALF the acceleration

4. Fnet = ma Newton’s Second Law
states that force is equal to mass times acceleration. In equation form, that is:
Fnet = ma
Fnet is the sum of all forces acting on an object
uses the unit newtons (N)
1 newton = 1 kg*m/s2
An object’s mass is the amount of matter it contains
uses the unit kilograms (kg)
A object’s acceleration is its change in velocity – this could be speeding up, slowing down, or changing direction
uses the unit meters per second per second (m/s2)

5. Fnet = ma Fnet = (2.40 kg)(0.90 m/s2) Fnet = 2.16 N Try it out…
If a 2.40 kg object is accelerating at 0.90 m/s2, what is the net force acting on the object?
Fnet = ma
Fnet = (2.40 kg)(0.90 m/s2)
Fnet = 2.16 N

6. Rearrange your equation…
when looking for acceleration:
a= F net m
when looking for mass:
m= F net a

7. Try it out… a= F net m m= F net a a= 2000 N 1000 kg
What acceleration is produced by a force of 2000 N applied to a 1000 kg car?
If a truck accelerates at 4.5 m/s2 with an applied force of N, what is the mass of the truck?
a= F net m
m= F net a
a= N 1000 kg
m= N 4.5 m/s2
a=2 m/s2
m= 2700 kg

8. Mass Vs. Weight Weight is a force, measured in newtons
weight is really a measure of the gravitational force between you and the Earth
FW = mg (weight = mass x gravity)
This is why the newton has units of kg*m/s2
on Earth, a 1 kg mass has a weight of (1 kg)(9.8m/s2) = 9.8 N
often shown on free body diagrams as FW instead of Fg
varies with location – your weight on Earth is different than your weight on the moon
Mass is the same everywhere – your mass on Earth is the same as your mass on the moon

9. Practice, Practice, Practice!
You have the rest of class to work on the practice problems.
Anything you don’t finish is HOMEWORK – due THURSDAY.