Name: _____________________________ Date: _____________ Period: _______
7th and 8th Grade Science
Mr. Vorstadt & Mrs. Yennie
st
Newton’s 1 Law of motion
1. You are an astronaut in space far away from any gravitational field,
and you throw a rock as hard as you can. The rock will:
slowly slow down and stop
continue at the same speed forever
Explain your answer. [3]
2. Mrs. Yennie and her classes are playing putt-putt. One of the holes
looks like the drawing below. The golfer must use the metal rim to
guide the ball toward the hole. Mrs. Yennie guides hers around the
rim as shown. When the ball leaves the rim at the opening, which path
will the ball follow, and why? [3]
3. Think of and describe three examples from sports in which a force
changes the velocity of an object or person. [3]
nd
Newton’s 2
law of motion
F
M
A
1. If you were to apply a force of 15N to a medicine ball that weighs 5
kg, what would its acceleration be? How about one that weighs
10kg?
Hint F= ma SHOW WORK [3]
2. If Mrs. Carey throws your graded homework assignment at you
2
with a force of 8N, and the homework accelerates at 5 m/s , what
is the mass of the homework?
Hint F= ma SHOW WORK [3]
2
3. You are playing baseball and the ball is accelerating at 5m/s off
your bat. If the original net force of 5N is tripled, what will be the
ball’s new acceleration?
Hint: a= F/m. SHOW WORK [3]
2
4. Take the same baseball as above, accelerating at the same 5m/s .
If the original net force of 5N is quadrupled, what will be the ball’s
new acceleration?
Hint: a= F/m. SHOW WORK [3]
5.
Sir Isaac Newton's only discovery was the three laws of motion.
True
False
6. The formula F=ma means "force equals motion times acceleration."
True
False
7. According to the first law, an object that is sitting still will stay that way.
True
False
8. One word that sums up the first law is
Motion
Force
Acceleration
Inertia
9. A Newton is equivalent to one:
kg m /s
kg m2/s
kg m/s2
kg m2/s2
10. How much force is required to give a 2000 kg car an acceleration of 3.0 m/s2 ?
2000 N
8800 N
667 N
6000 N
11. If you were to travel to a different planet:
your weight and mass would both change.
your weight and mass would not change.
your weight would change but your mass would not change.
your weight would not change but your mass would change.
12. An unhappy individual is trying to slide a 100 kg desk across a wood floor. He
pushes with a force of 800 N but the desk does not move. One can conclude that
the force of friction is:
more than 800 N.
more than 980 N.
exactly 800 N.
) exactly 980 N.
Test Your Newton Knowledge! Quiz Answers
st
Newton’s 1 law:
1. The answer is (b), continue at the same speed forever.
st
This is the definition of the 1 law.
2. The ball will follow path (2). The ball will continue to
follow its natural “inertial path”, and because of the lack
of unbalanced forces it will move in a straight line.
nd
Newton’s 2 law:
1. F= ma, thus for a 5 kg ball, a=3 m/s, and a 10kg ball,
a= 1.5 m/s.
2. F=ma, thus m= 1.6 kg.
2
3. a=F/m, so multiply by 3 and divide by 2 to get 7.5 m/s .
2
4. a=F/m, so multiply by 3 and divide by .5 to get 30 m/s .
rd
Newton’s 3 law of motion
1. While driving over here to teach you this physics lesson, I watched as
a bug hit my windshield. I knew immediately that this was a
rd
demonstration of Newton’s 3 law, because the bug hit my windshield
and my windshield hit the bug. The question is which of the two forces is
greater: the force on the bug or the force on my windshield?
2. You are playing paintball with a friend. When you fire the paintball
gun, it recoils slightly. As it is fired, the compressed air from your CO
2
canister pushes the paintball forward, and the paintball pushes your gun
backwards. The acceleration of your paintball gun is:
a. greater than the acceleration of the paintball.
b. equal to the acceleration of the paintball.
c. less than the acceleration of the paintball.
Explain your answer.
3. Study the drawing below between the two soccer players and the ball.
All three events are occurring at the same time. Identify the two pairs of
action-reaction forces. (Note: it does not matter what force is the action
or the reaction.)
nd
Newton’s 2 law:
1. F= ma, thus for a 5 kg ball, a=3 m/s, and a 10kg ball, a= 1.5 m/s.
2. F=ma, thus m= 1.6 kg.
2
3. a=F/m, so multiply by 3 and divide by 2 to get 7.5 m/s .
2
4. a=F/m, so multiply by 3 and divide by .5 to get 30 m/s .
rd
Newton’s 3 law:
rd
1. The forces are the same. This is the definition of the 3 law. The
bug just has a smaller mass and cannot withstand the larger
acceleration of the windshield.
2. The answer is (c), less than the acceleration of the paintball. The
forces are the same, but because the gun has a much larger mass
than the paintball, the acceleration of the gun will be smaller.
3. The action-reaction forces are:
a. Foot A exerts a force on ball B to the right, and ball B exerts
a force equal in size to the left on foot A.
b. Foot B exerts a force to the left on ball B, and ball B exerts a
force equal in size to the right on foot B.
NSF North Mississippi GK-8 13
Rubber Band Car Guidelines
You will be working with a partner to design and construct your own
rubber band powered car. The car should be designed as to maximize
distance traveled with the energy stored in its rubber band. There will be
no time stipulations on the race, so each car may move as slowly as
desired. Design criteria:
1. Only one rubber band will be allowed to power your car. If the
one you are given breaks, you will be given another.
2. The models will be no more than 12” wide.
3. Nothing that was designed for or previously used as a wheel is
allowed. This includes things such as Lego wheels, matchbox
wheels, or any kind of preformed wheel.
4. Ideas for allowable wheels include CDs, DVDs, bottle caps,
plates, plastic/metal/wood lids of various sorts, etc.
5. You will have access to various kinds of tape, pencils, and small
nails. If you need any other materials you must bring them
yourself or specifically request it after the first day.
6. Each pair of students will be allowed three runs of their car. A
run consists of a windup and a release of the rubber band car.
If your car spins out and only travels a foot that still counts as
a run.
7. The longest of the three runs will be the one that is used to
determine a winner. The pair with the highest average of their
three runs will also be a winner.
8. Be creative! Points for creative and interesting designs will be
awarded, even if they do not work as desired.
NSF North Mississippi GK-8 14
Name: _______________________________
PowerPoint Worksheet
on
Newton’s Laws of Motion
For what is Sir Isaac Newton famous? (You can list more than one thing.)
What is needed to change the motion of an object?
Pushing your friend on a swing is an example of a balanced or
unbalanced force?
Inertia is the ___________________ of an ____________________ to
resist ____________________ in its state of ___________________.
Which would have more inertia: a box filled with air or a box filled with
cement? (Hint: which would have more mass?)
What can you do to double the force of a certain thrown ball? (There can
be more than one answer.)
What is an example of Newton’s Third Law you experience in your daily
life?
NSF North Mississippi GK-8 15
Physics 221 Worksheet: Chapter 4, Newton's
Laws of Motion
1) An automobile is at rest on a level road Which of the following is false?
a) No forces act on the car.
b) The resultant force on the car is zero.
c) The normal force is equal to the weight of the car.
2) The car in problem 1) will remain at rest until:
a) a forward force of any magnitude is applied.
b) a forward force greater than the weight is applied.
c) a forward force greater than the friction force is applied.
3) The acceleration of an object is:
a) directly proportional to the unbalanced force and mass.
b) directly proportional to the unbalanced force and inversely proportional
to the mass.
c) inversely proportional to the unbalanced force and directly proportional
to the mass.
4) The MKS unit of force is __________ and the MKS unit of mass is _________.
5) A newton is equivalent to one:
a) kg m /s
b) kg m2/s
c) kg m/s2
d) kg m2/s2
6) The force that actually accelerates an automobile forward is:
a) the force applied to the car by the motor.
b) the force applied to the road by the wheels
c) the force applied to the wheels by the driver.
d) the force applied to the wheels by the road.
7) The direction of the force in the previous problem is:
a) forward
b) backwards
c) upward
d) downward
8) A 1.0 kg physics book weighs:
a) 1.0 kg
b) 9.8 kg
c) 1.0 N
d) 9.8 N
9) How much force is required to give a 2000 kg car an acceleration of 3.0
m/s2 ?
a) 2000 N
b) 58800 N
c) 667 N
d) 6000 N
10)The same force is applied for the same amount of time to a 2000 kg car and
a 4000 kg truck, both initially at rest.
a) The car travels twice as far as the truck.
b) The car travels four times as far as the truck.
c) The truck travels twice as far as the car.
d) Both travel the same distance.
Ans: 1-a, 2-c, 3-b, 4-(N, kg), 5-c, 6-d, 7-a, 8-d, 9-d, 10-a
Physics 221 Worksheet: Chapter 4, Laws of
Motion (Part 2)
1) If you were to travel to a different planet:
a) your weight and mass would both change.
b) your weight and mass would not change.
c) your weight would change but your mass would not change.
d) your weight would not change but your mass would change.
2) An unhappy individual is trying to slide a 100 kg desk across a wood floor.
He pushes with a force of 800 N but the desk does not move. One can
conclude that the force of friction is:
a) more than 800 N.
b) more than 980 N.
c) exactly 800 N.
d) exactly 980 N.
3) kg m/s2 is a valid unit for
a) mass.
b) weight.
c) acceleration.
d) velocity.
4) A net force of 5000 N gives a certain acceleration to a 2000 kg car. How
much net force is required to give the same acceleration to a 4000 kg truck?
a) 4000 N
b) 2000 N
c) 2500 N
d) 0000 N
5) A package is sliding down a frictionless ramp which is inclined at a 30º
angle to the horizontal. Its acceleration:
a) is 9.8 m/s2.
b) is 4.9 m/s2.
c) depends on the mass.
d) is none of the above.
6) A car is travelling at a constant speed of 25 m/s.
a) The applied force must be equal to the weight of the car.
b) The applied force must be greater than the air resistance.
c) The applied force must be greater than the weight of the car.
d) The applied force must be equal to the air resistance.
7) The force of gravity acting on an object is called its
a) weight.
b) mass.
c) acceleration.
8) When you stand on a scale with both feet it reads 80 kg. If you stand on one
foot it will read
a) 80 kg.
b) less than 80 kg.
c) more than 80 kg.
9) The scale in problem 8 is reading your
a) weight.
b) mass.
Ans : 1-c, 2-c, 3-b, 4-d, 5-b, 6-d, 7-a, 8-a, 9-b
Physics 221 Worksheet: Chapter 4, Laws of
Motion (Part 3)
1) You are sliding two boxes across the floor by applying force F to box A as
shown above. The force that box A exerts on box B is
a) qual to F.
b) greater than F.
c) less than F.
2) The same force is applied to the same object on Earth and on the Moon. The
acceleration is
a) greater on the Earth.
b) greater on the Moon.
c) the same in both places.
3) John weighs 100 N on Earth and Mary weighs 100 N on the Moon.
a) John’s mass is greater than Mary’s.
b) Mary’s mass is greater than John’s.
c) John and Mary have the same mass.
4) John weighs 100 N on Earth and Mary weighs 100 N on the Moon.
a) John is a child and Mary is an adult.
b) Mary is a child and John is an adult.
c) John and Mary are both children.
d) John and Mary are both adults.
5) A 10 kg box is hanging from two massless scales as shown above.
a) Scale A reads 10 kg and scale B reads zero.
b) Scale A reads zero and scale B reads 10 kg.
c) Scales A and B may have different readings but the sum must be 10 kg.
d) Scales A and B each read 5 kg.
e) Scales A and B each read 10 kg.
6) A 10 kg box is hanging from two massless scales as shown above.
a) Scale A reads 10 kg and scale B reads zero.
b) Scale A reads zero and scale B reads 10 kg.
c) Scales A and B may have different readings but the sum must be 10 kg.
d) Scales A and B each read 5 kg.
e) Scales A and B each read 10 kg.
Ans: 1-c, 2-c, 3-b, 4-a, 5-e, 6-c