Skate Park Practice Problems

Skate Park Lab 1. Do you think the Skater will make it over the first hump? (No friction on the track) No, because his potential energy will be converted to thermal energy No, because he doesn’t have enough potential energy Yes, because all of his potential energy will be converted to kinetic energy Yes, because some of his energy will be potential and some kinetic

Skate Park Lab 2. Do you think the Skater will make it over the first hump? (lots of track friction) No, because his potential energy will be converted to thermal energy No, because he doesn’t have enough potential energy Yes, because all of his potential energy will be converted to kinetic energy Yes, because some of his energy will be potential and some kinetic

Skate Park Lab 3. Do you think the Skater will make it over the first hump? (No friction on the track) No, because his potential energy will be converted to thermal energy No, because he doesn’t have enough potential energy Yes, because all of his potential energy will be converted to kinetic energy Yes, because some of his energy will be potential and some kinetic

Skate Park 4. Do you think the Skater will make it over the first hump? (lots of track friction) No, because his potential energy will be converted to thermal energy Yes, if not too much energy is converted to thermal Yes, because all of his potential energy will be converted to kinetic energy Yes, because some of his energy will be potential and some kinetic

5. In the next moment, the KE piece of the pie gets larger, then The Skater is going up hill (left) The Skater is going down hill (right) There is no way to tell

6. In the next moment, the KE piece of the pie gets larger, then The PE part stays the same The PE part gets larger too The PE part gets smaller There is no way to tell C 7

7. In the next moment, the KE piece of the pie gets larger, then The Skater will be going faster The Skater will be going slower There is no way to tell

1. The dotted line on the chart shows the energy of the Skater, where could she be on the track? The point E is Zero PE The track is saved, but you have to change the skater to the girl. It is the default track, but I used the pause to place her at the very top of the track and moved the track so that she reaches zero PE (nearly) Answer C 9

2. The bar graph shows the energy of the Skater, where could she be on the track? Answer D 10

3. The pie graph shows the energy of the Skater, where could she be on the track? KE B PE Answer B 11

4. If the ball is at point 4, which chart could represent the ball’s energy? KE PE A. B. C. D. 2 1 3 4 The track is saved, but you have to select the ball and give it maximum mass to see the pie well. I used the loop track with the ball skater and made it more massive. The answer is C A is at 1 or 3 B is at the lowest point on the track  C 12

5. If a heavier ball is at point 4, how would the pie chart change? KE No changes The pie would be larger The PE part would be larger The KE part would be larger PE 2 1 3 4 B Change the ball’s mass to show this 13

6. As the ball rolls from point 4, the KE bar gets taller 6. As the ball rolls from point 4, the KE bar gets taller. Which way is the ball rolling? At 4 Next step 2 1 3 4 You will need to Zoom out on the bar graph window to see the top of the bars Up Down not enough info 14

7. The Energy chart of a boy skating looks like this How would you describe his speed? He is at his maximum speed He is stopped He is going his average speed He is going slow He is going fast A 15

8. The Energy chart of a boy skating looks like this How would you describe his speed? He is at his maximum speed He is stopped He is going his average speed He is going slow He is going fast C Have the students predict by drawing the charts for B, D and E then show the next slide 16

9. Select a letter for each: stopped, slow and fast B A C C B A A slow B stopped C fast 17

Energy vs Position 10. Sketch this energy position graph. Label where the 5 spots, A-E, could be PE KE A He is going his maximum speed He is stopped He is going his average speed He is going slow He is going fast C C E D D B B 18

Emech at 1 + W = Emech at 2 mgh1 = mgh2 1. How high will pendulum rise? A) Less than h B) h C) More than h h From Tanner/Dubson CU Boulder Assuming no energy lost to anything else B Emech at 1 + W = Emech at 2 mgh1 = mgh2 Reference level (h = 0) Pendulum height 19