Collisions Lab

Purpose:
In this lab we focused on the differences between what an elastic and inelastic collision is. As a result we learned which is better conserved, momentum or energy. To find out whether momentum or energy is better conserved and see the differences between inelastic and elastic collisions, we tested both collisions. We took two cars, a ramp, and a labquest machine to record the velocity of one of the cars as it moves to create a collision with the other car. From there we record the momentum and kinetic energy of each car and the total.
                     

Key Information:

 Before performing these collisions we learned a couple terms that may help us in understanding momentum. Vectors and scalars both deal with magnitude but vectors also have direction. In the first collision we performed an example of an elastic collision, which is when objects collide and bounce off. The second collision we performed was the inelastic collision, which is when objects collide and stick together. To calculate the momentum we use the equation P=mv. P stands for momentum, m stands for mass and v stands for the velocity. To find the kinetic energy we use K= 1/2mv^2.

                      Elastic Collision:

                      Inelastic Collision:

Key Conclusions:

 As a result we learned that momentum is better conserved because the momentum total before is equal to the momentum total after. In other words, it is better conserved because when one cart is moving to the right(positive) and the other is moving to the left(negative) they cancel out which makes the momentum 0 or better conserved. This connects to why direction is important for vectors. In solving for kinetic energy the positives and negative might not always cancel out, so we have to make sure we know the direction an object is moving when dealing with the kinetic energy in collisions.

Real Life Connection:

An example of an inelastic or elastic collision would be car accidents. When a cars gets into an accident sometimes one bounces off from the other or they either stick together. When one car "bounces off" from the other car its momentum continues on into the other car, causing it to move a little more after it has been hit.

Rubberband Cart Lab

Purpose: In this lab we understood the big question: How are energy and velocity related? To answer this question we used an air hockey like machine, rubber band, cart, and motion sensor. We would pull back the cart with the rubber band .01 meter back until we did .05 meters. By doing this we were able to record the velocity of the cart going through the sensor from .01 m to .05 m. We tested two trials for this lab.

Key Information:
We repeated the same procedure twice, so we pulled back the red cart .01 m, then .02 m, then .03 m, then so on until .05 m. After recording our measurements for velocity we averaged the velocity squared. By using the graphing app we were able to get a graph like this:

With this lab we figured out a visual that helps us visualize the transfer of energy from one form to another.For example, in this lab we used a rubber band to push the cart. The visual, LOL Chart, helped us see the transfer from the rubber band to the cart.

Key Conclusion:
From this graph we were able to find its slope = .528 and put it into y=mx+b form--> y=.528x + .005
This is where we figure out the relationship between energy and velocity. Instead of y=mx+b we put it into K= 1/2 mv^2. K stands for the kinetic energy which is used when an object is moving, like in this lab we measured the kinetic energy when the cart moved passed the sensor. We use 1/2m because the slope = 1/s mass of an object and the v^2 is used because we are using velocity squared to make the equation become linear. We were also able to derive another equation: Ug = (m)(g)(h). Ug stands for gravitational energy, m stands for force and h stands for the distance from the object to the ground.This is how energy and velocity are related.

Real World Connection:
A roller coaster is an example of this lab because it involves both kinetic/spring energy and gravitational force. The roller coaster car is like the cart in the lab and the rubber band is like the spring that helps push the roller coaster car, which explains why spring energy is involved. Gravitational force is used because the roller coaster car is off the ground.