Name ______
Acting on Impulse
NOTE: the procedures in each of the mini labs involve different processes related to impulse. Even so, you should be able to use reason to determine your answers. Keep this in mind as you answer the questions.
Problem – How does the length of a straw affect the impulse and the velocity of a cotton swab if the force is held constant?
Materials – Meter stick, 2 cotton swabs, 2 straws, tape
Procedure
1.Tape two straws together side by side. With a pencil or pen mark a circle around the middle of one of the cotton swabs. Place the marked cotton swab (called the “far swab”) into the end of a straw that will be farthest from your mouth. Place the other swab (called the “near swab”) into the “near” end of the other straw.
2.Place the two straws into your mouth with the swabs at opposite ends, hold the straws level and blow outward.
3.Compare the distance (approximate) the two cotton swabs traveled. Repeat the steps until you get consistent results. You must specify the swab you are referring to as “near” or “far” in all the following questions! Describe the results herein words:
Trial # / Near Swab ( ) / Far Swab ( )1.
2.
3.
Developing the Ideas
1.What was each swab’s velocity before you began to blow? The momentum of an object is directly related to its velocity, so what was the momentum of each swab before you began to blow?
2.How does the horizontal distance traveled by the swabs relate to their horizontal velocity as they exited the straws?
3.Assuming that both swabs had the same mass, which swab had the largestmomentum as it exited the straw? Note: momentum = mass x velocity
4.Compare the size of the applied forces acting on the two swabs.
5.Compare the times that the applied forces act on the two swabs (time in the tube).
6.Impulse = force x time. Which swab had the largest impulse acting on it? Which swab had the larger change in momentum as it left the straws?
7.Hypothesize: How would the results of the experiment change if both straws were cut in half?