The Egg Lab involves placing an egg on a cart and then releasing the cart at the top of a ramp. This ramp makes an angle of 60 degrees with the horizontal.
First, we had to determine how much force the egg could withstand. We set up the track and used a motion detector to determine the acceleration while the egg rolled down the track. We then weighed the egg to learn its mass.
Here Daniel is recording the mass and the acceleration
We found the mass of the egg to be 0.05 kg, the cart (which we also massed) was 0.27 kg; and from the LabQuest we determined that the acceleration at which the egg breaks was 2.67 m/s^2. With this information, the force can be calculated because F=ma. F=0.05(2.67)= 0.13 N.
We used the LabQuest to determine acceleration
However, we later learned that 2.67 is the acceleration of the egg as it was going down the ramp, but this wasn't the acceleration we should've used. We should've used the egg's acceleration after it hits the book. Because of this, our force is incorrect. What we should've gotten was a value between 10 and 15 N.
Afterwards, we calculated the force the wall exerts on the cart. We determined this value with our known measurements and then we proved it by letting the cart slide down the ramp.
The acceleration for an object going down the ramp would be gsin(theta), so in this case 10sin(60). This equals 8.66. The mass of the egg and the cart combined is 0.32 kg. 0.32(8.66) = 2.77 N. Since the wall exerts the force in the opposite direction our final answer would be -2.77 N.
Here, we are setting up the experiment
We will determine the actual force the cart hits the books with
When we carried out the experiment with a force detector, we found the maximum force to be -56.38 N. The collision time was 0.04 s. According to the LabQuest, the impulse was -1.21 J. Since we know J=Ft, we can solve for the average force. -1.21=F(0.04). -1.21/0.04=F= -30.25 N.
Based on the impulse equation, we know that for the egg to survive the impact, the collision should take a longer time. This is because force is inversely proportional to time. Based on the momentum equation, in order for the egg to survive the impact, the collision should occur at a lower velocity. This is because force is directly proportional to velocity.
In the next step of this lab, we modified the cart so that the egg would survive the impact. We placed tape and sandpaper on the wheels to increase friction and slow down motion (decreasing velocity). We also added a plate to the front of the car, which we taped cotton and a bubble wrap to. These materials function as an airbag (increasing collision time). We also made a basket for the egg which we filled with cotton, which will absorb the impact so that the egg doesn't experience much force.
Here we are modifying the cart so that the egg can survive
We also used a force detector to determine how much the force was decreasing.
Here is one of our trials
This was one of our most successful trials
We estimate that the velocity the car will hit the wall with is 0.5 m/s. Accel=v/t. Accel x t=v. 8.66 x 0.06= 0.5 m/s. We estimate that the impulse will be around 0.39 J. The force the car will hit the wall with should be 6.5 N (J/t, 0.39/0.06). We estimate that the impact will last 0.06 s.
Therefore, in summary: 1-Force to break an egg: 10-15 N. 2-Mass of an egg: 0.05 kg. 3-Time for egg to safely come to rest: 0.2 s. 4-Final velocity of egg: 0 m/s. 5-Velocity of egg just before impact: 4.6 m/s. 6-Accel: 8.66 m/s^2. 7-Force: 6.5 N. 8-Duration of impact: 0.06 s. 9-Total change in momentum/impulse: 0.39 J.
We then did the actual experiment to see whether the egg breaks. And it didn't break! Our max force was 5.56 N, and our impulse was 0.202 J. The collision time was 0.06 s. Which means our average force was 3.37 N. The egg's velocity before impact was 4.6 m/s. Accel: 8.66 m/s^2. Final velocity: 0 m/s.
This is the data for the cart sliding down the ramp with the egg.
In conclusion, this lab was fun as well as educational, and it helped us understand momentum.