1. Investigation 3.1: Law of Inertia
Purpose: To learn whether heavy objects fall faster or slower
than light objects
Name: _______________________
Part I: Background – Read the Background and answer
the questions on the next page.
A force is a push, pull, or any action that has the ability to change motion. If you see a ball sitting on the ground, you have to apply some kind of force in order to get it moving. Once it is moving, it will keep moving until another force changes its motion. It takes a force to start motion and to stop motion.
One of the most important scientists in history was named Isaac Newton. He developed three important Laws of Motion to describe the way the world works. Newton’s First Law is also called the Law of Inertia, which states: An object at rest will stay at rest and an object in motion will stay at motion at the same velocity unless acted on by an outside force. Inertia is the property of an object to resist change in its motion. If an object is hard to start moving, or to stop moving, it has a lot of inertia. Objects with less mass have less inertia. This makes sense if you think about it – if you have a bowling ball and a golf ball sitting on your desk at rest, which one is harder to start rolling? The bowling ball is harder to start rolling – it resists changes in motion – because it has more inertia – and this is because it has more mass. The opposite goes for the golf ball.
Key Question:
Why are heavier objects harder to start or stop moving?
HS-PS2-1

2. A object with more inertia will resist ________________.
Pre-Lab Questions
If an object has more mass, it has __________ inertia. Therefore, the variables of mass and inertia are ______________ related.
A object with more inertia will resist ________________.
A bowling ball is harder to start moving than a golf ball because it has more inertia. Would a bowling ball or a golf ball be harder to stop? Why? ____________________________________________________________________________________________________________________
What units are we measuring in this lab? Do we need to complete any conversions?
Unit of Distance =
Unit of Time =
Unit of Speed =
HSN-Q.A.1
HAS-CED.A.1
WHST

3. Distance through beam (cm) Time through photogate (s)
Part II: Procedure
In this experiment, you will launch cars of different masses downhill, to see if having a greater or smaller mass will make the car fall down the hill faster or slower. Write your hypothesis about this below:
Make sure your SmartTrack is attached to the fourth hole up from the bottom.
Make sure the photogate is on the 100 cm mark.
Drop cars of different masses – with 0, 1, 2, 3 marbles – downhill. Align them evenly as seen in the picture.
Do four trials by launching cars with 0, 1, 2 and 3 steel marbles. Record time through the photogate in the table below.
Calculate the speed for each car, and record below.
Part III: Data
# of marbles
Distance through beam (cm)
Time through photogate (s)
Speed (cm/s) 1 2 3

4. Part IV: Analysis
Create a speed vs. number of marbles graph below. Don’t forget to label the axes and give the graph a title.
HSF-IF.C.7

5. Part V: Conclusion – Mini Claim, Evidence, and Reasoning (CER)
We will write it in sentence form instead of paragraph form. This will be part of the lab grade.
QUESTION: Why are heavier objects harder to start or stop moving?
CLAIM: Your answer to the question based on your results.
____________________________________________________________________________________________________________________________________________________________________
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EVIDENCE: Your data that led you to the claim statement.
__________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
REASONING: Information from sources, such as textbook, internet, notes that says your evidence is correct.
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