1. Newton’s 2nd Law

2. Newton’s 2nd Law identifies the relationship between the net force exerted on an object and the object’s acceleration
When more than one force is acting on an object at a time, to find the net force you must find the sum of the forces with respect to direction

3. The formula we will use is F = ma
F is the net force in Newtons
m is mass in kilograms
a is acceleration in m/s2

4. If net force then acceleration If mass then acceleration
If we rearrange the formula to read a = F/m then we can see that an object’s acceleration is directly related to its net force and inversely related to its mass
If net force then acceleration
If mass then acceleration

5. Example
Determine the acceleration of an object when a 12 N net force is applied to a 3 kg object.
F = ma
a = F/m
a = 12 N / 3 kg
a = 4 m/s2

6. Determining Net Force
The net force is the vector sum of all the forces which act upon an object
Fnet = 200N, down
Fnet = 20N, left
Fnet = 400N, up

7. Today’s Equations The 3 equations to use are:
F = ma Fgrav = mg Ffrict = μ•Fnorm
The last formula is a Honors formula: μ (mu) stands for the coefficient of friction and will either be given in a problem or it can be solved for using the third equation
*Note: 3rd equation not on reference sheet

8. Example: Solve for unknowns

9. Example: Solve for unknowns
100 N, up .1
10.2 kg
.98 m/s2, right
10 N, right