Unit 4 Exam Review: 8.6ABC
Define velocity: measurement of speed and the direction of an object
Define magnitude: size
What is the formula for finding acceleration? A= F/m
Define:
Newton’s 1st Law:
An object at rest stays at rest or an object in motion stays in motion until unbalanced
forces act upon it.
Newton’s 2nd Law:
Acceleration of an object depends on the object's mass and the magnitude of the force
acting upon it (F = ma).
Newton’s 3rd Law:
For every action there is an equal and opposite reaction.
In the experiments that we completed in class, what was the force that was always acting
on the car or the washers?
FRICTION
Give an example of Newton’s 3rd Law:
(Action/Reaction)
Leaning against the wall
Give 3 examples that demonstrate Newton’s 1st Law:
(Think about the experiments we did in class.)
1. A car & a penny crashing into a book. The penny kept going.
2. Sliding a washer into a stack of washers. Only the bottom washer moved.
3. An astronaut throwing a baseball in Space.
How do you calculate force?
F = (m)(a)
Let’s say a car and a truck are traveling at the same speed down a hill toward a stop sign.
Which vehicle will require more force to stop and which will require less force? Explain
your reasoning. The truck would require more force because it has a larger mass. It would
be more difficult to stop a truck vs. a car.
Determine the speed the car travels at 2, 3, and 4 seconds. Is it accelerating? If not, then
what is it doing? 5 m/s, it is not accelerating, it is moving at a constant speed.
What is inertia?
The tendency of a physical object to remain still or continue moving unless force is applied.
I placed a quarter and a notecard on top of a cup, and then flicked the card. What would
happen to the quarter? Why? Explain which law is being demonstrated. The quarter would
fall into the cup and the card would go flying because I only applied a force the card, not
the quarter. Newton’s 1st Law would be demonstrated.
To travel from De Leon to San Antonio it is 185 miles. The trip takes about 4 hours to get
there. What is the velocity? (Remember velocity has 2 parts.)
S= d/t
S= 185 mi/ 4 hours
S= 46.25 mph South
What is the net force and the direction?
2N Right
What happens when an unbalanced force acts on an object?
If the object is at rest, it will move. If the object is already in motion, it could speed up,
slow down or change direction.  ACCELERATE 
An empty soup can and a full soup can were both pushed with the same amount of force.
Which one would have the greatest change in speed? Explain.
The empty can would move faster because it has less mass. With the same force, an object
with less mass will have more acceleration. The full soup can may move longer, but it did
not have the greatest change in speed.
What will happen to the boat if the current increases to 2 m/s south?
The boat will slow down but will continue to move North at 1 m/s.