Name _____ KEY ____________________________________ Date _________ Period ______
Newton’s 3 Laws
Newton’s Law
Law in Your Words
Example of the Law
1st Law
Inertia
Voyager coasting through space
2nd Law
F = ma
Lighter shopping cart moves faster
than full cart
3rd Law
Action-Reaction Forces
Pushing off of a spaceship moves
you and the ship backwards
1.
In space, an untethered astronaut could float out endlessly into space. Use newton’s 1st
and 3rd laws to explain why this is the case.

2.
While watching people dive into the pool from the high dive, you realize that using a
diving board to spring into the air before a dive is a good example of Newton’s 3rd law of
motion. Explain how a diving board illustrates Newton’s third law of motion.

3.
The rocket pushes out exhaust and is propelled forward by the reaction force.
When Jane drives to work, she always places her purse on the passenger’s seat. By the
time she gets to work, her purse has fallen on the floor in front of the passenger seat. One
day, she asks you to explain why this happens in terms of physics. What do you say?

6.
The basketball and your hand, the basketball and the floor and your feet and the
floor are all action-reaction forces.
In order for a rocket to accelerate through space, there must be an equal and opposite
force. How does a rocket accomplish this in the vacuum of space?

5.
The diving board reacts to your downwards force by pushing you upwards.
You dribble a basketball while walking on a basketball court. List and describe the pairs
of action-reaction forces in this situation.

4.
An untethered astronaut will float endlessly because there is nothing to provide a
reaction force to stop their motion. This will also lead to them moving with
inertia, based on the 1st law.
This is due to inertia. When the car stops, the purse does not, instead it continues
forward as it was before the stop until it hits the floor.
Your shopping cart has a mass of 65 kilograms. In order to accelerate the shopping cart
down an aisle at 0.3 m/s2, what force would you need to use or apply to the cart?
F = ma = (65 kg)(0.3 m/s2) = 19.5 N