SECTION I: INTRODUCTION

TITLE: Skatepark Energy Lab

OBJECTIVE:

Explain concept of Mechanical energy using kinetic and gravitational potential energy.

EQUIPMENT NEEDED:

● Computer

PROCEDURE:

(Please see below for procedures in the data).

SECTION II: DATA

Activity 1

Many factors affect the skater’s path, the length of the downhill, the weight of the skater, how long the track is, and his height after a dip or a jump.

To build a challenging, fun, and safe track, the jumps must be easily cleared, the inclines can’t be too steep, and the change in slope from down to up cannot be too sharp.

The best graphs that help understand how the track is successful in terms of the conservation of mechanical energy is the Bar graph and the energy vs. time graph. The bar graph is very useful because it actively shows the dynamic change from potential to kinetic back to potential energy as the skater is moving. The energy vs. time graph is like the bar graph but records the whole track into a easy to analyze graph that allows the viewer to piece together the path of the skater by looking at the potential versus the kinetic energy.

Conservation of mechanical energy means that the total energy in a system remains constant, only the potential and kinetic energy are changing in relation to one another.

The track is successful in terms of Conservation of Mechanical Energy because the skater starts with potential energy as height and transforms it to kinetic energy as he falls but uses this kinetic energy to rise again. Although the skater doesn’t end at the same height he started, the track uses the kinetic energy of drops to let the skater clear gaps and uses potential energy to let the skater gain speed to make it more fun.

Things that need to be considered when designing any track are the starting height, the ending height, the angles of the inclines, the speed at the top of any hills, and the speed of the object at the end of the track.

DATA TABLES:

Activity 2 1.

Pie chart

Prediction Simulation Explain differences

1 all blue all blue no difference

2 all green all green no difference

3 all blue all blue no difference

4 ¼ blue ¾ green ⅓ blue ⅔ green

the difference is probably because it had a little more kinetic energy than I thought it would at that point in the track

2. a. I think the pie charts will stay the exact same. b. I think they would be very similar, if not the same due to the fact that the energy would be the same proportion regardless of the weight of the object. If it is frictionless, it will be the same. c. It was just as a predicted. The pie chart was exactly the same with the heaviest skater as it was with the ball which was the lightest object.

3. a. I believe that the pie charts will lose kinetic energy because energy will be lost in the friction. The skater will move slower and lose energy.b. They will be different due to the loss of energy from the increased friction.c. Most of the potential energy was replaced by thermal energy. And also he was unable to go on the loop because of all the friction.d. They both had the same exact pie charts again, but the pie charts both changed because of the friction adding thermal energy and replacing a lot of the potential energy.

4. a.

b. I think it will be full potential at the top then be half potential half kinetic at the second point then full kinetic at the third and fourth and then 20 percent potential and 80 percent kinetic at 5th and then half and half at 6th and then half and half at 7th and then 100 percent potential at 9th.d. I was right about the first two. The next two never reached 100 percent kinetic. They were about half and half. There was also a little thermal energy as it approached the 6th point due to the incline. It held that thermal energy from 6th to the end when it became 100 percent potential.

5. They are displaying the same exact information, the only difference is the visual aspect of the graphs. The bar graph shows the total and the three types of energy. You can use the length of bars to predict a rough estimate of each type of energy knowing that they all add up to the total. Same thing in the pie chart, it’s just that the pie chart is a little easier to work with.

6.a. 2nd dotb.1st and last dotc. between 2nd and 3rd and 4th and 5thd. between 2nd and 3rd dot and 4th and laste.between 1st and 2nd dot and 3rd and 4th dot

7. max speed: position 5stopped: position1 and position 12average speed: position 2.8, 6, 8, and 10.5slow: positions 2, 7, and 11fast: positions 3-5, and 9-10

a. My ideas were pretty accurate.b. I would make sure they remembered that kinetic energy meant movement and potential movement meant it stays still. Where they intersect is where they are equal. I would probably get the average in the middle of where the kinetic slope is where the potential intersects. If it is there is 0 kinetic it is not moving. If there is 100 percent kinetic it is moving its fastest.

8. You can use the charts to predict the direction of the ball by looking at the the patterns in the graphs. You can also see when it is at rest and when it is moving by seeing when its kinetic energy is 0 or not and when the potential energy is full or not.

a. During every simulation no matter how simple you can use these bars and graphs to check it. b. You can tell if the ball is moving faster or slower by the difference in kinetic energy. If there is a big difference in kinetic energy compared to potential. For example, if the line for kinetic is way above the potential for a longer period, it is going faster. So on and so forth and vice versa.c. Predict what the pie charts will look like on a pie chart on this frictionless ramp. Use different

skaters and predict if the pie chart will change.

CALCULATIONS:

Activity 3

Helpful hints: You can take measurements by using the Show Path button, then click on any purple dot to see the values. Make sure if you change any variables (like mass, location, character, etc) that you clear the path to get new purple points.

1. Play with the features shown to the right and the purple dot data to understand what the data means. Then,

a. Explore how the values change when you move the PE reference line.i. Kinetic energy is inversely proportional to potential energy. When potential

energy is at its height, which is when the skater is highest on the ramp, kinetic energy is at its lowest point. When the potential energy reference line is moved to a point higher than the skater, all potential energy transfers to kinetic energy.

b. Explore how the values change when you change the Skater. Remember, changing the skater only changes the mass.

i. i. Less mass means less energy required to produce the same effect on a ramp; energy decreases with mass.

2. Explain what is meant by the value called height.a. Height is the distance above a surface.

3. Consider the following situation: You put the Skater on a track, Show Path and display the purple dot data. How could you predict the values for another place on the track?

a. Describe what you would have to measure:i. PE = MGH

1. The greater the height, the greater the potential energy, if the height is zero, then, because potential energy and kinetic energy are inversely proportional, kinetic energy would be greatest. You would have to

measure for mass, gravity, and height ii. KE= .5MV

1. You would have to know the objects kinetic energy and mass to calculate for velocity.

iii. V= D/T1. Calculate for velocity by dividing distance by time.

b. Show an example of your proposed calculations for each value: KE, PE, TE, speed. i. KE: Determine the Kinetic energy of a 500kg roller coaster train which moves at a speed

of 20 m/s. M = 500 kg, V = 20 m/s Step 1: Substitute the values in the below kinectic energy formula: Kinetic Energy: Ek = ½ mv2

= ½ x 500 x 202 = 0.5 x 500 x 400 Kinetic Energy: Ek = 100000 Joules or 1 x 105 Joules ii. PE: Determine the Potential energy of A cat had climbed at the top of the tree. The Tree is 20 meters high and the cat weighs 6kg. How much potential energy does the cat have? m = 6 kg, h = 20 m, g = 9.8 m/s2(Gravitational Acceleration of the earth) Step 1: Substitute the values in the below potential energy formula: Potential Energy: PE = m x g x h = 6 x 9.8 x 20 Potential Energy: PE = 1176 Joules iii. Speed: Determine the speed of Lisa Carr: Q: While on vacation, Lisa Carr traveled a

total distance of 440 miles. Her trip took 8 hours. What was her average speed?To compute her average speed, we simply divide the distance of travel by the time of travel.c. Test your ideas and include a screen capture with the purple dot data shown for both

points that show that your calculations are correct. Show a corrected example of calculations if the data didn’t match your ideas.

i. The higher the height, the greater the potential energy. Here is a picture to prove this: As you can see, the blue bar, potential energy, is at it’s height because the skater is as high up on the ramp as he can go.

1. Describe what you think will change in your calculations if you move the Skater to Jupiter.1. Describe what you would have to measure. i. You would have to account for the change in gravity.1. Show an example of your proposed calculations for each value: KE, PE, TE, speed. i. Kinetic energy, potential energy, and speed would all vary based

upon the increase in gravity; they would all be greater. Thermal energy would remain the same because it’s internal energy.

1. Test your ideas and include a screen capture with the purple dot data shown to support your calculation or show corrected examples.

Here the energy required has clearly increased as you can see in the image below:

Potential energy being greatest at it’s height:

Here the energy required has clearly increased on Jupiter.

Activity 4 Directions:

1. This graph was made with the 75 kg Skater Guy riding on the track shown. Without using the simulation, talk with your partner to predict the answers to these questions. Record your predictions! 1a. Where was he at time zero? At 7 seconds? At 8 seconds? 5 seconds?0s= 1m7s=68s=75s=5

b. If his maximum height is 4 m, what is his height at time zero? At 7 seconds? At 8 seconds?5 seconds?0s= 0m5s= 2 m7s= 3.5m8s= 4m

c. What is his speed at time zero?At 7 seconds? At 8 seconds? 5 seconds?0s= 0m5s= 2 m7s= 3.5m8s= 4m

d. Sketch what the graph would look like between 13 and 15 seconds

3. Without using the simulation, talk with your partner to predict the answers to these questions about the same Track, Skater and Starting point as #1. Record your predictions!

a. Sketch what the graph might look like between 0 and 9 seconds if the Track Friction Was turned on.

b. How do you think his location will be affected? Think about both horizontal and vertical location. His location will change.

c. How do you think his speed on the track will be affected? He speed will increase.

d. Test your ideas using the simulation and make corrections to your predictions.

4. Consider if the 60 kg Skater Gal rode on the same Frictionless Track and Starting point.a. How do you think her position, speed and energy will compare to the Guy’s? She will have a greater speed and more energy.

b. Sketch what the graph might look like between 0 and 5 seconds.

c. If you used the same amount of track friction, how would your answers to question threecompare? The position, location, speed, and energy will change.

RESULTS:

During this lab, we were able to explain the Conservation of Mechanical Energy concept using kinetic and gravitational potential energy. We were also able to design a skatepark using the concept of mechanical energy. We were also able to describe energy from position and certain speeds and describe how the changing skater affected these situations, as well as how changing the surface friction affects this. We also predicted positions and estimates of speeds from charts and we looked at a position of an object using these charts to predict direction of travel and change in speed. Lastly, we used energy-time graphs to estimate a location for the skater on a track, calculate the speed or height of the skater, and predict energy distribution for tracks with and without friction at a given time. Our data can be displayed throughout the data tables we created and the graphs located in our data.

CONCLUSION:

We reached our objectives because by the end of each activity, all of the objectives were accomplished through the steps that we took when manipulating our tracks or analyzing the graphs. We effectively performed all of the activities using this simulation. Our data is shown in the graphs we created and examined to answer the questions. This lab can be improved by spending more time examining this data and breaking up the parts so all of it isn’t done at once.