1

What is Newton’s 2nd Law of Motion?A net force (unbalanced force) acting on an object causes the object to accelerate.

F=ma

Ms. Bates, Uplift Community High School

2

Wait a minute! We already know this formula….

Ms. Bates, Uplift Community High School

What is the force in this equation? What does the 10 stand for?

w=m x 10

3

REMEMBER: What is Acceleration?

rate of change in velocity speed up, slow down, change direction

Ms. Bates, Uplift Community High School

4

What is Directly Proportional?Both variables increase or decrease at the same timeHINT: both variables will be in the

numerator

Ms. Bates, Uplift Community High School

5

What is Inversely Proportional?As one variable increases the other will decrease by its inverse.HINT: one variable is in the

numerator and the other is in the denominator

Ms. Bates, Uplift Community High School

6

Demonstration: Newton’s 2nd

What happened when a small force was applied to the ball?

What happened when a large force was applied to the ball?

Ms. Bates, Uplift Community High School

There was a small acceleration

There was a large acceleration

7

Demonstration: Newton’s 2nd

What happened when a force was applied to a ball with a small

mass?

What happened when the same force was applied to a ball with a

large mass?

Ms. Bates, Uplift Community High School

There was a large acceleration

There was a small acceleration

8

What is the relationship between force mass and acceleration?

Acceleration is directly proportional to the net force

Ms. Bates, Uplift Community High School

F=ma

€

a =F

mRearranged…

9

What is the relationship between force mass and acceleration?

Ms. Bates, Uplift Community High School

F=ma

€

a =F

m

Acceleration is inversely proportional to the mass (remember: mass resists change in motion

because of inertia!!)

Rearranged…

10 Ms. Bates, Uplift Community High School

Class Practice

1. A net force pushes an object to the right, in which direction does it accelerate?

2. If an object is not accelerating (constant velocity) what is the net force acting on it?

3. If you double the force on the object, what happens to acceleration if you keep the mass the same?

4. If you 1/3 the mass of an object, what happens to acceleration if you keep the force the same?

5. If you quadruple (multiple by 4) the mass of an object, what happens to the acceleration if you keep the force the same?

6. If you multiply the acceleration by 6, what must happen to the mass if the force is the same? 11