4.1 Video Motion Analysis using “Tracker”
Screenshots of with graphs for the trial:
(a) Displacement – time graph
(b) Velocity – time graph
(c) Acceleration – time graph
There could be wind blowing when the car was moving, so it could move less or more than the calculated value. The resistive forces were also not calculated, and hence the resistive force would cause the car to move a shorter distance.
9. Calculate the average velocity for your car during the period after the spring fully releases.
Trial 1: Velocity = Displacement/Time = 8m/9.2s = 0.870m/s (3 significant figures)
Trial 2: Velocity = Displacement/Time = 8m/9.1s = 0.879m/s (3 significant figures)
Trial 3: Velocity = Displacement/Time = 8m/8.9s = 0.899m/s (3 significant figures)
10. What force causes your car to stop?
Friction between the ground and the wheels of the car, as well as friction between the parts of the car. Air resistance also reduces the distance which can be traveled by the car.
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?
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.
(a) Displacement – time graph
(b) Velocity – time graph
(c) Acceleration – time graph
4.2 Data Analysis
1. Which wheels are you drive wheels?
Back wheels
2. What is the circumference of your drive wheels?
37.7cm
1. Which wheels are you drive wheels?
Back wheels
2. What is the circumference of your drive wheels?
37.7cm
3. How far will your car travel in one rotation of the drive wheels?
37.7cm
4. How many rotations (on average ) were there in each run?
4. How many rotations (on average ) were there in each run?
21
5. How much string is used in one rotation of the drive wheels? Show how you calculated this.
5. How much string is used in one rotation of the drive wheels? Show how you calculated this.
0.5cm x 3.14159265358979323846364338=1.57cm(3s.f)
6. The release of the lever is the power stroke. What is the length of your vehicles power stroke? (Length of string released)
16.5cm
6. The release of the lever is the power stroke. What is the length of your vehicles power stroke? (Length of string released)
16.5cm
7. Calculate how far your vehicle will travel during the power stroke. Show your
calculations.
power stroke/string used in 1 rotation=no. of rotations
16.5cm/1.57cm=10.5(3s.f.)
no. of rotations * circumference of wheel=how far vehicle will travel during power stroke.
power stroke/string used in 1 rotation=no. of rotations
16.5cm/1.57cm=10.5(3s.f.)
no. of rotations * circumference of wheel=how far vehicle will travel during power stroke.
10.5*37.7cm=395.85cm≈4m
8. Compare the answer to #7 to the distance your measured during your car’s
power stroke. Discuss possible reasons for different valuables.
There could be wind blowing when the car was moving, so it could move less or more than the calculated value. The resistive forces were also not calculated, and hence the resistive force would cause the car to move a shorter distance.
9. Calculate the average velocity for your car during the period after the spring fully releases.
Trial 1: Velocity = Displacement/Time = 8m/9.2s = 0.870m/s (3 significant figures)
Trial 2: Velocity = Displacement/Time = 8m/9.1s = 0.879m/s (3 significant figures)
Trial 3: Velocity = Displacement/Time = 8m/8.9s = 0.899m/s (3 significant figures)
10. What force causes your car to stop?
Friction between the ground and the wheels of the car, as well as friction between the parts of the car. Air resistance also reduces the distance which can be traveled by the car.
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?
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.
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