Fan Cart Lab

Purpose: The purpose of this lab was to answer the Big Question, "What is the relationship between mass, force and acceleration?"We answered this question throughout our let when we tested the acceleration of each fan cart mass.

How?: In this lab, we started by measuring the mass of fan cart (300 g). Then we recored the acceleration of the fan cart without any added mass, and recorded our data in the Time vs. Velocity graph by measuring the slope. We then repeated this many times, each time with a different mass. We started to notice that the slope of the line in our graph changed each time.

Graph: These two graphs represent the different accelerations of the fan cart. The first one, represents the fan cart's initial  acceleration without any added mass (300 g). The second graph is the fan cart's acceleration with the greatest amount of mass added (1300 g).

Conclusion: Based on our data, we concluded that there is an inverse relationship between acceleration and mass. As mass increases, acceleration decreases, and vice versa. The equation used to represent this would be F=m • a
This lab is related to Newton;s Second Law of Motion.

Real World: This lab relates to pushing a shopping cart at the grocery store. When you first walk in to the grocery store and grab an empty cart, it is easy to push because there is nothing inside. The force you exert would make the cart accelerate faster because of its low mass. However, after you are done shopping, the cart becomes harder to push because you have put many items inside. If you exert the same amount of force onto the full cart as you did to the empty cart, it would accelerate slower because of its higher mass.

Hover Disk--Interaction Diagrams

Purpose: The purpose of this lab was to test motion without the force of friction. We used a hover disk because it floats on a pocket of air, essentially allowing it to glide on a frictionless surface. We used Newton's 3 Laws to answer the Big Question, "What gives rise to a change in motion?" This lab focused on the different forces being applied to an object--force pairs. This lab is summed up in Newton's Third Law.

How?: In this lab, the object we applied force to was the hover disc. First, we turned on the hover disc (removing friction) and pushed it across the floor to the other person. Then we repeated this with the hover disc off, which added the element of friction. After completing these motions, we looked at the interaction diagrams and filled in arrows to each object which represented the type of force being used.

Conclusion--Interaction Diagrams: As you can see in the two diagrams below, the Force of Gravity (pink) and Normal Force (purple) are ALWAYS present between the earth, the two people, and the hover disc. The Normal Force is only present between the person and the hover disc when they are in contact. Also, notice that once the hover disc was turned off, the Force of Friction (blue) is now added between the hover disc and the earth.

Real World: An example of this lab would be comparing ice skating to walking. When we walk, the Force of Friction is present between us and the ground (hover disc off). This force enables us to keep a steady pace and firm footing on the ground, because without it, we would glide on forever instead of walking. However, ice skating is a little different. Since ice skaters are on blades as well as a slick ice surface, there is less friction between the person and the ice, enabling them to glide smoothly over the surface.

Impulse

Purpose: In this lab, we explored the new concept of impulse, and used our data to answer the Big Question, "What is the relationship between impulse, force and time?" This lab is connected to our previous collision lab, and we found impulse by going off of our knowledge of momentum.

How?: We started this lab the exact same way we started the last one, except on one side of the track we had a Logger Pro to record the car's velocity and a Force Probe Ring of the other side. We measured the car's velocity before and after the collision, and also measured the area of the dip in the "Force vs. Time" graph.

Graph: We used the velocity we collected to help us calculate momentum, "P".
We needed to find the momentum before and after the collision to find impulse, "J".
Impulse=ΔP
J=Pf - Pi

Conclusion: The area of the dip in our "Force vs. Time" graph was about -0.3613.
Our calculated impulse was -0.301. The impulse is about equal to the area. This is an example of Newton's Third Law of Motion--"For every action, there is an equal and opposite reaction." The concept of impulse is the relationship between force, time and momentum.

Real World: This lab relates to the popular middle school game, "Wall Ball." When a kid hits the ball against the wall, it comes back to the other player with an equal amount of force and momentum.