Download Guided Practice—Student Copy

SMART Curriculum Lesson Plan
Science – Grade 10 & 11 Exit
§ Objective 5 TEKS 4.B §
The student will demonstrate an understanding of motion, forces, and energy..
TAKS Objective 5 Students need to understand force and motion in order to comprehend
the concepts of speed ,waves, and energy transformations .The study of motion, forces,
and energy is necessary for understanding the physical world. Whether riding in a car,
turning on lights, or listening to the radio, we are continually surrounded by examples of
Newton ’s laws of motion and energy transformations.
TEKS Integrated Physics and Chemistry (4B)Science Concepts. The student knows
concepts of force and motion evident in everyday life. The student is expected to
investigate and describe [applications of ] Newton ’s laws such as in vehicle
restraints, sports activities, geological processes, and satellite orbits.
Objectives Anything that moves, stays put is following one of Newton’s laws. Students
must have an understanding of the concepts of inertia, force, mass, and acceleration, in
order to understand Newton’s laws. Once these concepts are understood, the applications
are seen everywhere. Or as the TEA puts it in the information booklet “The integration
of biological and earth science concepts with the study of forces, motion, and energy may
be seen in items that address ideas such as osmosis, blood pressure, muscle activity,”
weather, and plate tectonics.
Teach Critical Attributes of the Concept
IPC (4B) investigate and describe [applications of] Newton ’s laws such as in vehicle
restraints, sports activities, geological processes, and satellite orbits.
1.Newton’s First Law
A.Smash up Barbie
Materials: Barbie, roller skate or dynamics cart. Large rubber band Brick (stacked
textbooks will work as well but aren’t as much fun)
Seat Barbie on a roller skate or cart in such a way as to simulate driving a car. At a
distance of 4-6 feet give the “Barbie car” a good push towards the “Brick wall”. Have
students describe the results. Next take the rubber band and stretch it around Barbie’s
waste and the roller skate to simulate a seatbelt. Repeat the above procedure and describe
the results.
B. Coin in beaker trick.
Materials: Coin, index card, small beaker
Have students place an index card over the top of a beaker. On top of the card, place a
coin. Using their index finger have the students snap the card quickly and describe the
results.
2. Newton’s Second Law
A. Constant mass, changing force
Materials: Dynamics cart or roller skate, string, pulley with clamp, weights, stopwatch.
Attach a string to the cart and the other end of it to a weight. Arrange a pulley on the
edge of the table as pictured.
Release the weight and time how long it takes the cart to roll forward 1 meter along the
table. This time add another weight to the hanging weight and repeat the experiment.
Add one more weight and see what happens. How does this effect the time for the cart to
move forwards?
B. Constant Force changing mass
Materials: Same as above
Remove all of the extra weights from the hanging mass, leaving just the original weight.
Add a weight now to the cart on the table. Release the cart and time how long it takes to
go 1 m. Add another weight to the cart and run the experiment again. Repeat a third
time with an additional weight. How does increasing the mass effect the time it takes for
the cart to move one meter if the force accelerating the car (the hanging mass) remains
constant?
3. Newton’s Third law
Straw Balloon races
Materials: Fishing line, plastic straws, masking tape, balloons
Take a straw and cut it in half and thread a fishing line through it. Tie a fishing line
across the room and stretch it tightly. Repeat with another fishing line making them
parallel with each other. Have students blow up balloons of various shapes and sizes
without tying them. They should just hold them in place until ready to race. When it is
their turn, attach their balloon to the straw hanging on the fishing line with masking tape.
Repeat for the other line. When both balloons are ready, let the racing begin. Why do
the balloons move along the fishing line?
Teach Critical Attributes of the Skill
Before students can understand Newton’s laws, they must understand the
following concepts. Force – a push or pull, mass -- the amount of matter in an object,
Velocity – speed in a given direction, and acceleration – the rate at which velocity
changes.
Newton’s first law also called the Law of inertia is fairly easy for students to
grasp. I like to call it the law of lazyness. Things want to keep on doing what they were
already doing. Make sure students grasp the idea that when Barbie did not have a
seatbelt on she kept on moving forward because that was what she was doing to begin
with (inertia). Wearing her seatbelt, kept her from going to the land of misfit toys
because this provides a force on her which causes her to slow down over a longer period
of time. Wearing the seatbelt is actually where Newton’s first and second laws come
together. Ask the students for other examples of Newton’s first law. I like to discuss
traveling around a corner at fast speeds and the feeling of being pushed outwards as an
example of inertia. When you round a corner in a car, your body wants to keep on
moving forward but a force acts on the car causing it to make the turn. The friction
between your body and the seats act on your lower body but nothing acts on your upper
body and you have this feeling of being pushed outwards.
The cart with the hanging mass, is a good way for students to obtain a grasp of
Newton’s second law, f = ma. It is imperative that students have lots of practice working
with this equation. They must also play close attention to their units. Force is measured
in Newtons in the S.I. system of units. One Newton is the amount of force necessary to
accelerate a 1 kg mass at the rate of 1 m/s. Mass in the equation is always measured in
kg, and acceleration is always measured in m/s2 (this means m/s/s, or meters per second
per second). They must be prepared to convert g to kg. Students need to grasp that when
the forces on an object are unbalanced, the object will accelerate (Newton’s 2nd law), if
the forces remain balanced, the object will keep on doing what it was already doing
(Newton’s 1st law).
Newton’s 3rd law is often called the law of action and reaction. Another way it is
stated is “you can’t touch without being touched”. That can confuse students though as
objects that do not touch each other still obey Newton’s 3rd law (the gravitational
attraction between the earth and the moon). Students need to understand the idea of an
action reaction pair. If there is an action force, there has to be a reaction force. The
physics textbook author, Paul Hewitt, has a great worksheet covering this topic (ask your
schools’ physics teacher for a copy). Ask students to come up with action reaction pair
examples. Some examples: Action-a man pushes down on the floor; Reaction-the floor
pushes up on the man. Action-bat hits a baseball, Reaction-baseball hits the bat. In the
balloon race activity, the action was the air pushing on the balloon, the reaction was the
balloon pushing on the air (not, the balloon goes forward). The balloon accelerates
forward because there is an unbalanced force acting on it – the air (Newton’s 2nd law).
Guided Practice—Teacher Copy
1. While driving in a car, the car makes a sharp turn. You feel your body being pushed
to the side of the car. Which of Newton’s three laws, best explains this occurrence?
a. Newton’s 1st law
b. Newton’s 2nd law
c. Newton’s 3rd law
The correct answer is a. Your body continues to do what it was already doing.
2. An unbalanced force of 50 N is applied to a 2000g mass. What will be the resulting
acceleration of the mass?
a. 100 m/s2
b. .025 m/s2
c. 25 m/s2
d. 40 m/s2
The correct answer is c. F = m a so a = F/m ,mass must be in kg so 2000g = 2 kg, 50N /
2kg = 25 m/s2
3. The earth pulls on a rock with a force of 50 N. If this is the action force, then what is
the reaction force?
a. The rock falls to the earth
b. The rock pulls up on the earth
c. The rock pushes on the hand that is holding it
d. The rock falls and lands on my foot
The correct answer is b. The formula for action reaction is quite simple: If force A acts
on object B, then force B acts on object A. Objects do not have to be touching to obey
Newton's third law.
4. An unbalanced force acts upon a block with a mass of 3000 g. This causes the block
to accelerate at the rate of 15 m/s2. How much is the force acting on the block?
a. 45000 N
b. 200 N
c. .2 N
d. 45 N
The correct answer is d. F = ma, F = 3 kg (convert g to kg) x 15 = 45 N
5. The rate at which velocity changes is called
a. Acceleration
b. Velocity
c. Speed
d. Inertia
The correct answer is a. Acceleration is the rate at which an objects velocity changes.
Guided Practice—Student Copy
1. While driving in a car, the car makes a sharp turn. You feel your body being pushed
to the side of the car. Which of Newton’s three laws, best explains this occurrence?
a. Newton’s 1st law
b. Newton’s 2nd law
c. Newton’s 3rd law
2. An unbalanced force of 50 N is applied to a 2000g mass. What will be the resulting
acceleration of the mass?
a. 100 m/s2
b. .025 m/s2
c. 25 m/s2
d. 40 m/s2
3. The earth pulls on a rock with a force of 50 N. If this is the action force, then what is
the reaction force?
a. The rock falls to the earth
b. The rock pulls up on the earth
c. The rock pushes on the hand that is holding it
d. The rock falls and lands on my foot
4. An unbalanced force acts upon a block with a mass of 3000 g. This causes the block
to accelerate at the rate of 15 m/s2. How much is the force acting on the block?
a. 45000 N
b. 200 N
c. .2 N
d. 45 N
5.
a.
b.
c.
d.
The rate at which velocity changes is called
Acceleration
Velocity
Speed
Inertia
Independent Practice—Teacher Copy
1. A person in a head-on car collision, who is not wearing a seatbelt, continues to move
forward at the original speed of the car because of ______.
a. friction
b. inertia
c. gravity
d. weight
The correct answer is b. Objects want to keep on doing what they were already doing –
inertia.
2. A force of 125 N causes a mass to accelerate at the rate of 5 m/s2
How much is the mass?
a. 25 kg
b. .04 kg
c. 500 kg
d. 130 kg
The correct answer is a. This is a straightforward f = ma problem. M = f/a = 125/5 = 25
3. Forces that are equal in size and opposite in direction are ______.
a. gravitational forces
b. frictional forces
c. balanced forces
d. net forces
e. weak forces
The correct answer is c. Newton’s third law.
4. Which of the following 4 objects has the greatest inertia. All of the objects are at rest.
a. baseball
b. ping pong ball
c. football
d. bowling ball
The correct answer is d. Inertia applies to objects at rest as well as to objects in motion.
A bowling ball has the largest mass of the four objects listed. Therefore it wants to
remain at rest the most giving it the greatest inertia.
5. An archer pulls an arrow back in his bow and lets go allowing the arrow to fly rapidly
towards its target. If the action force is the arrow pushing against the bowstring, then
what is the reaction force?
a. The arrow pushing its way through the air
b. The bowstring against the arrow
c. The pull of gravity on the arrow
d. The target hitting the arrow
The correct answer is b. If the arrow pushes against the bowstring, the bowstring pushes
equally in an opposite direction against the arrow.
Independent Practice—Student Copy
1. A person in a head-on car collision, who is not wearing a seatbelt, continues to move
forward at the original speed of the car because of ______.
a. friction
b. inertia
c. gravity
d. weight
.
2. A force of 125 N causes a mass to accelerate at the rate of 5 m/s2
How much is the mass?
a. 25 kg
b. .04 kg
c. 500 kg
d. 130 kg
3.
a.
b.
c.
d.
e.
Forces that are equal in size and opposite in direction are ______.
gravitational forces
frictional forces
balanced forces
net forces
weak forces
4.
a.
b.
c.
d.
Which of the following 4 objects has the greatest inertia. All of the objects are at rest.
baseball
ping pong ball
football
bowling ball
5. An archer pulls an arrow back in his bow and lets go allowing the arrow to fly rapidly
towards its target. If the action force is the arrow pushing against the bowstring, then
what is the reaction force?
a. The arrow pushing its way through the air
b. The bowstring against the arrow
c. The pull of gravity on the arrow
d. The target hitting the arrow