Download for every action there is an equal and opposite reaction

for every action there is an equal and
opposite reaction
Name_________________________________ Period_______________ Date______________________
Newton’s Three Laws of Motion
Study Guide
1. Gina is driving her car down the street. She has a teddy bear sitting on the back seat. A dog
runs in front of Gina's car, so she quickly applies the brakes. The force of the brakes causes
the car to stop, but the teddy bear continues to move forward until it hits the car's
dashboard.
The teddy bear did not stop at the same time as the car because of which Newton’s Law of
Motion? Newton’s 1st Law of Motion- an object (bear) will stay in motion until acted
upon by an unbalanced force (dashboard)
2. Newton's _Third_ law of motion states that "For every action, there is an equal and opposite
reaction."
3. Newton's __First__ Law of Motion states that "An object at rest tends to stay at rest and an
object in motion tends to stay in motion with the same speed and in the same direction
unless acted upon by an unbalanced force."
4. Trevor is pushing two boxes across a sidewalk. Box A has a mass of 4 kg. Box B has a mass
of 8 kg. According to Newton’s Second Law of Motion, if Trevor applies the same amount of
force to each box,
A.
B.
C.
D.
box
box
box
box
B
A
A
B
will move twice the distance of box A.
and box B will accelerate at the same rate.
will accelerate at twice the rate of box B.
will accelerate at twice the rate of box A.
5. When experimenting with the film canister rockets, the action was the downward push of the
film canister on the desk. What was the reaction force?
A. the upward force of the desk pushing on the film canister
B. the downward force of the film canister’s weight on the Earth
C. there is no reaction force
6. When the net forces equal 0 N, they are __balanced__.
7. ___Unbalanced___ forces cause an object to start moving. (Hint: Newton’s First Law of
Motion)
8. What is the difference between mass and weight? Gravity; mass is the amount of
matter that makes up an object; weight is the mass plus the amount of gravity
pushing down on the object.
9. What is the force that opposes motion between two surfaces that are in contact? (friction or
acceleration) friction
10.What is the net force of an object when you combine a force of 20 N north with a force of 15
N south? 5 N (north)
11. Albert Pujols (first baseman for the St. Louis Cardinals) and Mrs. Finley are traveling down
the hallways of the school in teachers’ chairs at the same velocity. Which person has the
most momentum? Why?
Albert Pujols has the most momentum b/c he has more mass and more inertia.
Name_________________________________ Period_______________ Date______________________
12.What is inertia and how is it related to Newton’s First Law of Motion?
Inertia is “want to,” it wants objects to keep going in a straight line at a constant
speed; Newton’s First Law states that objects will keep moving with inertia until acted
upon by an unbalanced force.
13.What is the force necessary to accelerate an 85 kg object at a rate of 6.3 m/s²? (Use your
FAM triangle.) F=a x m; F=85 x 6.3= 535.5 N
14.What is the acceleration of a 1,456 kg truck if a force of 47,320 N is used to move the
truck? (Use your FAM triangle.) a=F/m; a=47,320/1,456= 32.5 m/s²
15.Explain gravity (pg. 526). Gravity is a force of attraction between objects (due to
their masses).
16.If a softball and a bowling ball are dropped from the same height at the same time, and there
is no air resistance, which ball will hit the ground first? Why? (pg. 542) They would both hit
the ground at the same time b/c the acceleration due to gravity is the same for all
objects when there is no air resistance involved.
17.
18.
19. The equation a=F÷m represents Newton’s second law of motion. Based on this equation, if
balanced forces act on an object, what can be expected of the object’s acceleration?
0 m/s2 because it takes an unbalanced force to move or stop an object.
20. How does Newton’s third law of motion explain why a swimmer moves forward in the water?
The swimmer exerts a backward force on the water and the water exerts a forward force on
the swimmer, pushing the swimmer forward.