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IPS Unit 1.2 Newton’s Second Law
Name: _________________
WHAT DO YOU THINK?
 List three ways you could apply a force onto your partner?
Please don’t do it!
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
If Mr. Mellor pushed a tiny freshman as hard as he could, then
pushed a BIG senior as hard as he could, how would each move
differently during the push? (Don’t worry Mr. Mellor hasn’t
pushed a freshman in months!)
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GOALS FOR THIS
ACTIVITY
 Define force
 Identify the forces acting
on an object.
 Determine when the
forces on an object are
either balanced or
unbalanced.
 Compare amounts of
acceleration semiquantitatively.
 Can the same force move
a bowling ball and a ping
pong ball?
 Apply Newton’s Second
Law of motion to
situations in sports
activities.
 Apply the definition of
the Newton as a unit of
force.
Physics Words
 force (4.3)
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 newton, the unit
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 acceleration (chapter 2)
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 Newton’s Second Law (5.3)
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 mass
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 weight
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 force due to gravity
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 acceleration due to gravity
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FOR YOU TO DO
1. (Teacher demonstration) Hook a force meter to a car and pull it horizontally across the floor.
Get to work!!!
Make sure that the meter and string are always horizontal. Pull a few times trying to keep the force
at a constant 1 newton. A graph will be made showing the amount of force on the y-axis (up and
down) and time on the x- axis (left and right).
a) What do you observe, see, happening to the cart as it is pulled with a constant force?
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b) Why is it so difficult to pull at a constant 1 newton of force?
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Materials:
 Liquid accelerometer with
rubber band and laminate
 Cart
 Paper clip
 String
 Hanger
 Various masses
 One foot of tape
2. So let's try again. We can use gravity to help us out. Get the material listed above and set up as
shown.
a) By placing masses on the hanger we can let gravity pull the system down (the weight, force of
gravity, is what causes the system to move). A mass of 100 grams will apply a force of about 1
newton to the cart system.
b) So, add 50 grams to the hanger, making the total hanging mass 100grams. The force of gravity
pulling on the system will be 1 newton.
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3. Pull the cart back until the hanger is at the top of the table. Release the
cart and look at the liquid accelerometer as the cart is moving.
a) Sketch the shape of the water in the liquid accelerometer as it is
moving due to the falling mass, not as you stop it.
As a class we learned about what a liquid accelerometer tells us about the motion of an object.
Using that information answer the following question.
b) What does the liquid tell you about the motion of the cart while it is being pulled to the right?
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4. Repeat the process by pulling the cart with a constant force of 2 N by
placing another 100 gram mass on the hanger for a total of 200 grams
on the hanger.
a) Sketch the shape of the water in the liquid accelerometer to the
right.
b) How is it different from what you observed in "a" when the force was 1 N?
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c) What does the liquid tell you about the motion of the cart while it is being pulled to the
right in this case? Remember to think about what learned about liquid accelerometers.
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5. Repeat the whole process by pulling the cart with a constant force of 3 N, which means a total mass
of ____________grams will be hanging on the string.
a) Sketch the shape of the water in the liquid accelerometer to the
right.
b) How is it different from what you observed in "b" when the
force was 2 N?
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c) Based on your observations, complete the statement: "The greater the constant, unbalanced
force pulling on the cart, the……"
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d) In other words how does the size of the constant, unbalance force affect the motion of an
object?
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6 . Repeat step 2b and 2c, using the same amount of constant force, 2 N, to pull the cart of greater and
greater mass.
a) You should redo it so that the level of the liquid is fresh in your
mind. Start off with the cart by itself and a constant force of 2 N
(mass of is 200 grams). Sketch the shape of the water in the
liquid accelerometer to the right.
b) Add a 500-gram mass to your cart and leave the hanging mass
alone so that the force is still 2 N. Sketch the shape of the water
in the liquid accelerometer.
c) How is it different that what you observed in the last one?
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d) What does the liquid tell you about the motion of the cart?
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e) Repeat the process by adding another 500-gram mass and leaving
"B" alone. Record your results in the same manner as you did in
4b
.
f)
What happens to the acceleration of the cart as the cart becomes more and more massive?
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7. Based on your observations, complete the statement: "If the force acting on the cart is kept constant,
when mass is added to the cart, the cart …….."
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In other words if the same force is used to pull the cart, how does increasing the mass of the cart
affect the cart's motion?
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8. Let’s review: If the pulling force on an object is increased, the acceleration of the object:
increases
decreases
9. If the pulling force on an object stays the same, but the mass of the object increases, the acceleration
of the object:
increases
decreases
10. As a class read sections 5.1-5.3: pp. 59-61
11. Now your teacher will do three demonstrations. Write an explanation of how each deals with
Newton’s 1st law, 2nd law, inertia and mass.
a. Parlor trick: __________________________________________________________________
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b. Basket balls: _________________________________________________________________
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c. Jenga: _______________________________________________________________________
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Unit 1.2: Newton’s Second Law Reflection Questions
Remember to use any new vocabulary from this or previous activities!!
1. How does the size of the unbalanced force acting on the object affect the acceleration of the
object?
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2. How does the mass of the object affect its acceleration?
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3. Why does the mass matter when it comes to the acceleration of an object?
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4. In your own words what does Newton’s 2nd law mean to you?
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5. In other words if the same force is used to pull the cart, how does increasing the mass of the
cart affect the cart's acceleration?
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6. If the pulling force on an object is increased, why does the acceleration increase?
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7. If the pulling force on an object stays the same, and the mass increases why does the
acceleration decrease?
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