4. Data analysis

4.1 Video Motion Analysis using “Tracker” 

Paste screen captures here with the following graphs for each of the 3 trials:

Displacement – time graph

Velocity – time graph

Acceleration – time graph 

• NOTE!!! Area under Speed over time graph is distance travelled by the car (GRAPH 2 OF ALL RUNS). This is because, SPEED X TIME = DISTANCE. Thus, SPEED/TIME graphs are most important in this data collection process.

4.2   Data Analysis 

1. Which wheels are you drive wheels? (front or back)
Back

2. What is the circumference of your drive wheels?
Diameter = 5.5cm
Circumference = πd = π(5.5cm) = 17.3cm (3sf)

3. How far will your car travel in one rotation of the drive wheels?
17.3cm

4. How many rotations (on average ) were there in each run?
Number of rotations = Maximum distance travelled by car/circumference of rotation (=how much car will travel in one rotation) = 14m/17.3cm = 1400cm/17.3cm = 80 (rounded down from 80.9 ((3sf)) )

5. How much string is used in one rotation of the drive wheels? Show how you calculated this.
One rotation around axel = circumference of axel
Axel 
Diameter = 3mm = 0.3cm
Circumference = πd = π(0.3cm) = 17.3cm (3sf)

6. The release of the lever is the power stroke. What is the length of your vehicles power stroke? (Length of string released) 
72cm

7. Calculate how far your vehicle will travel during the power stroke. Show your calculations!!
(72cm/17.3cm) x 80 rotations = 333cm (3sf)

8. Compare the answer to #7 to the distance your measured during your car’s power stroke. Discuss possible reasons for different valuables.
Human errors like reaction timing may cause the possibility in different valuable. 
Inertia could have taken place, causing the car to move forward more than the calculated distance. 
The rotation of the string around the axle of the wheels could be rotated in slightly different position each time causing possible different valuables. 

9. Calculate the average velocity for your car during the period after the spring fully releases.
In average, 
Total distance of run: 14m
Distance car travels while lever is releasing: 10.5m
Total time of run: 10.5s
Time taken for lever to fully release: 5s
Distance traveled by car after lever is fully released: 3.5m
Time taken for car to travel 3.5m after lever is released: 5.5s
Distance/Time = Speed
3.5m/5.5s = 0.636m/s (3sf) = 2.29km/s (3sf)

10. What force causes your car to stop?
Friction between wheels & the ground & between axel & chassis.
Air resistance acting in the opposite direction of motion.
Weight of the mousetrap car weighing the car down.

11. The work done by a force is calculated by multiplying the force times the distance over which it acts. The work done on an object is equal to the change in its kinetic energy. Can you find a way to calculate the force of friction? Use equations and explain your steps. HINT: Be careful, you have calculated average velocity. How can you find the total amount of kinetic energy (immediately after spring release) if we assume the acceleration during coasting was constant?

Work done = Force x Distance
Kinetic energy = Work done

F = M x A
Where A = acceleration, M = mass, F = force. 
Acceleration can be found from finding the gradient of the velocity time graph

F= 0.233kg x 1m/s^2
F= 0.233N
According to Newtons third law (Third law: When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body), Reaction force = Opposite force (Friction force) = 0.233N

Work done = Force x Distance
Work done = 0.233 x 11 = 2.097J
12. Various experiments have been done to measure the potential energy available from the spring. One estimate is 0.65 Joules. Using your estimates of the maximum kinetic energy of your car and the work done by friction, discuss whether or not this is a reasonable value. Can you account for any differences in the forms of energy? You must justify all of your arguments.

This is not a reasonable value as there are many variables affecting the values like for example, the elastic potential energy is converted to not only kinetic energy but other energies like sound and heat. This made us disagree that the value is reasonable. The energy estimated could have been more than 2.097J.