UMUC NSCI 101/103
Lab 3: Newtonâ€™s Laws of Motion
On your own and without assistance, complete this Lab 3 Answer Form and submit it via
the Assignments Folder by the date listed on your Course Schedule (under Syllabus).
To conduct your laboratory exercises, use the Laboratory Manual that is available in the
classroom. Laboratory exercises on your CD may not be updated.
Save your Lab 3 Answer Form in the following format: LastName_Lab3 (e.g.,
Submit your document in a Word (.doc or .docx) or Rich Text Format (.rtf) for best
Experiment 1: Newtonâ€™s First Law
1. Record your observations for each type of motion from Step 4 in the space below. Comment on
where the water tended to move. If the water spilled, note which side it spilled from .
1. Explain how your observations of the water demonstrate Newtonâ€™s law of inertia.
2. Draw a free body diagram of your box of water from the situation in Procedure 4d. Draw arrows for
the force of gravity, the normal force (your hand pushing up on the box), and the stopping force
(your hand decelerating the box as you stop.) What is the direction of the waterâ€™s acceleration?
*Note, free body diagrams are discussed in depth in Lab 2: Types of Forces. See Figure 3 for a sample
diagram. Remember, the object is usually indicated as a box, and each force that acts upon the box is
indicated with an arrow. The size of the arrow indicates the magnitude of the force, and the
direction of the arrow indicates the direction which the force is acting. Each arrow should be labeled
to identify the type of force. Note, not all objects have four forces acting upon them.
Figure 3: Sample FBD
3. Can you think of an instance when you are driving or riding in a car that is similar to this experiment?
Describe two instances where you feel forces in a car in terms of inertia.
Experiment 2: Unbalanced Forces – Newtonâ€™s Second Law
Table 1: Motion Data for Experiment 2
d of M2
When you give one set of washers a downward push, does it move as easily as the other set? Does it
stop before it reaches the floor? How do you explain this behavior?
2. Draw a FBD for M1 and M2 in each procedure (Procedure 1 and Procedure 2). Draw force arrows for
the force due to gravity acting on both masses (Fg1 and Fg2), and the force of tension (FT). Also draw
arrows indication the direction of acceleration, a.
Experiment 3: Newtonâ€™s Third Law
1. Explain what caused the balloon to move in terms of Newtonâ€™s Third Law.
2. What is the force pair in this experiment? Draw a Free Body Diagram (FBD) to represent the
(unbalanced) forces on the balloon/straw combination.
3. Add some mass to the straw by taping some metal washers to the bottom and repeat the
experiment. How does this change the motion of the assembly? How does this change the FBD?
If the recoil of the rifle has the same magnitude force on the shooter as the rifle has on the bullet,
why does the shooter not fly backwards with a high velocity?