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Today you will create a presentation on gravity.  Each slide must be about the answer to the question.  Also, each slide should have an image illustrating the answer.

Use this site for your information.

Slides 1-7 can be found in the “What is Gravity” section.

Slide 1: Title, your name and your partner’s name.

Slide 2: What is gravity?

Slide 3: How strong is gravity compared to other forces?

Slide 4: What two factors determine the strength of the gravitational force?

Slide 5: How is the gravitational force related to distance?

Slide 6: What is the gravitational force equation and what does everything mean?

Slide 7: How does Einstein’s General Relativity explain gravitation?

Information for the following slides can be found in the Small Scale Effects, Large Scale Effects, and The other sections.

Slide 8: What is the strength of gravity on the moon compared to the earth?

Slide 9: How can anything fall without hitting the ground?

Slide 10: What is a black hole?

Slide 11: What is a gravitational wave?

Slide 12: How can you make fake gravity?

Open gravity force lab (http://phet.colorado.edu/simulations/sims.php?sim=Gravity_Force_Lab )

Part I: Force of Gravity

1. What is true about the force of m2 on m1, and the force of m1 on m2 (two things) __________________________________________________________________2. Set both masses equal to 25 kg, and set them both 4 m apart. You can move the masses and rulers.

3. What is the force of gravity? ___________________ Compare the following answers to this answer.
4. Keep the masses 4 m apart, but change one mass to 50 kg.
5. What is the new force of gravity? _____________________
6. How did it change (compared to #4)? ___________________________________
7. Change the 50 kg mass down to 12.5 kg.
8. What is the new force of gravity? _____________________
9. How did it change (compared to #4)? ___________________________________
10. Set both masses back to 25 kg, but move them so they are 8 m apart.
11. What is the new force of gravity? _____________________
12. How did it change (compared to #4)? ___________________________________
13. Given the two masses of 25 kg 8 m apart, how can you change one mass to get back to the answer in #4? _____________________________________________

Open my solar system (http://phet.colorado.edu/simulations/sims.php?sim=My_Solar_System)

Part II: Planetary Motion

I After the simulation loads click Start.

Sketch and describe (your paper) what you see in this simple sun-planet system.

Specifically, what happens to the central object (the Sun)?

Can you explain why the central object moves?

HINT: Is gravitational attraction only the sun pulling on the planet?

Does the planet orbit in a perfect circle? Is the sun at the center?

II Click Stop and then select 3 bodies. Then Start

Sketch a complete cycle (orbit)

Watch the ‘funny’ object closely

What is it doing? Describe and explain.

Could this be the Earth/Moon/Sun system? (Try unchecking Show Traces.)

Is there anything you are uncomfortable with in the simulation? Explain.

Can you explain the difference in the moon’s path when it is on the right

side of the Sun compared to on the left side? (Turn Traces back on.)

III Click Stop and then select 4 bodies. Then Start

Describe what is happening to the inner planet, why.

IV Click Stop and then select 2 bodies again.

Change the mass of the ‘planet’ to 100 units and then Start.

Explain how the motion is different from Part I.

Ever hear of a binary star?

Repeat with both bodies at 200 units of mass.

V Click Stop and then select 3 bodies again.

Change the masses of bodies 2 and 3 to 5 units each and Start.

Watch for several orbits and explain what’s happening.

Open lunar lander (http://phet.colorado.edu/simulations/sims.php?sim=Lunar_Lander)

Part III: Lunar Lander

1. Play the game. Your goal is to have the maximum number of landings before you run out of fuel. Try to keep the landings soft and avoid the boulders.
2. How many landings did you achieve? ___________________________________
3. What was difficult about this game? ____________________________________ __________________________________________________________________

Quiz Practice

Calculating Potential Energy

1. A 50 kg diver stands at the top of a 10m diving board. What is his potential energy?

2. When the diver jumps and is half way down to the water, what is his potential energy?

3. When the diver reaches the water, what is his potential energy?

Calculating Kinetic Energy

1. A 50 kg diver stands at the top of a 10m diving board. What is his kinetic energy?

2. When the diver jumps and is moving at 5 m/s. What is his kinetic energy?

3. When the diver reaches the water, what is his potential energy?

Conservation of Energy

1. A roller coaster at the top of its first hill has 100,000J of potential energy. How much potential energy will it have when it reaches the bottom of the hill?

2. How much Kinetic Energy will the roller coaster have at the bottom of the hill?

3. A 2 kg bowling ball sits at the top of a ramp that is 10m high. If it rolls down the ramp, what will its kinetic energy be?

4. A 2 kg bowling ball sits at the top of a ramp that is 10 m high. What is its potential energy half way down the ramp?

5. Starting from rest, a 2 kg block of wood slides a distance of two meters down a frictionless slope, as shown above. What is the kinetic energy of the block at the bottom of the slope?

Calculating Momentum

1. A 3 kg bowling ball moves down the lane at 3 m/s. Calculate its momentum.

2. A 50 kg skier jumps off a 50 foot jump at 5 m/s. Calculate her momentum.

Elastic Collisions

1. A 3 kg bowling ball moving down the lane at 3 m/s hits another 3 kg bowling ball and comes to a stop. How fast will the second bowling ball travel after it’s been hit?

2. A 3 kg bowling ball moving down the lane at 3 m/s hits a 6 kg bowling ball and comes to a stop. How fast will the second bowling ball travel after it’s been hit?

Inelastic Collisions

1. A 100 kg lineman moving at 3 m/s hits a 50 kg quarterback that is standing still. If the lineman keeps ahold of the quarterback, how fast will they be traveling after the hit?

2. A 50 kg fisherman jumps into a 100 kg boat at a speed of 2 m/s. After the fisherman lands in the boat, how fast does the boat and fisherman travel?

Run the simulation linked here.

1. Pull the bottom of the ramp down to the ground and measure the height of the skateboarder when he is at his highest.  Calculate his potential energy if his mass is 75 kg (PE = mgh).  Turn on the Energy vs. Position or Energy vs. time graph and see if you calculation is right.

2. Run the simulation until he is at the bottom of the ramp.  What is his Kinetic Energy at the bottom (just read it from the graph or use Conservation of energy)?

3. Where did the Kinetic energy in #2 come from?

4. Change the skater to a the girl, measure the girl’s highest point and calculate her potential energy at the highest point.

5. What will be the girl’s kinetic energy at the bottom?

6. Run this simulation.  Draw a picture in your notes and explain how this simulation shows energy conservation?

7. Where is the potential energy the greatest and the least?  Where is the kinetic energy the greatest and the least?

8. Run this simulation. Draw a picture in your notes and explain how this simulation shows energy conservation?

9. Is energy conserved when friction is present?

Potential and Kinetic Energy Problems.
Do these in your notebook.

1. A 0.2 kg apple in a tree that is 10 m high, has what potential energy?

2. A 0.2 kg apple in a tree that is 5 m high has what potential energy?

3. When the apple in the previous problem hits the ground, what is its potential energy?

4. A 600 kg roller coaster at the top of the highest point on its track which is 50 m, has what potential energy?

5. If the roller coaster in the previous problem went down the track to half of its highest hight, what would its potential energy be?

6. If the roller coaster goes all the way to its lowest point, what is the potential energy of the roller coaster?

7. A 3 kg ball is rolling 2 m/s. How much kinetic energy does it have?

8. Determine the kinetic energy of a 600-kg roller coaster car that is moving with a speed of 20 m/s.

9. If the roller coaster car in the above problem were moving with twice the speed, then what would be its new kinetic energy?

10. If the roller coaster car in the above problem came to a stop, what would its kinetic energy be?

Tricky Problems

11. Missy Diwater, the former platform diver for the Ringling Brother’s Circus, had a kinetic energy of 12 000 J just prior to hitting the bucket of water. If Missy’s mass is 40 kg, then what is her speed?

12. A 900-kg compact car moving at 60 mi/hr has approximately 320 000 Joules of kinetic energy. Estimate its new kinetic energy if it is moving at 30 mi/hr.

13. What is the kinetic energy of a 0.2 kg apple that falls from a 10 m high tree? What is the apple’s energy when it is 5 m above the ground?

Return quiz, go over difficult problems.

Potential and Kinetic Energy Notes [Page 16]

Problems [Page 17]:

Calculating Potential Energy

1a. A skier with mass 50 kg sits on top of a 100m high hill.  What is his potential energy?

1b. A skier with mass 50 kg skis down the hill and is now 50m high.  What is his potential energy?

1c. A skier with mass 50 kg skis down the hill and is now 25 m high. What is his potential energy?

1c. A skier with mass 50 kg skis down the hill and is now at the bottom of the hill. What is his potential energy?

1d. Where did all his potential energy go?

Calculating Kinetic Energy

2a. What is the kinetic energy of a 2 kg bowling ball traveling at 1 m/s?

2b. What is the kinetic energy of a 2 kg bowling ball traveling at 2 m/s?

2c. What is the kinetic energy of a 2 kg bowling ball traveling at 3 m/s?

2d. What is the kinetic energy of a 2 kg bowling ball traveling at 4 m/s?

2e. How is kinetic energy related to velocity?

3a.  If you drop a 1 kg rock off a building that is 300 m high, what is the rock’s potential energy at the top of the building?

3b. What is the rock’s kinetic energy at the top of the building?

3c. What is the rock in #1a’s Potential energy half way down the building?

3d. What is the rock in #1a’s potential energy when it reaches the bottom of the building?

3e. Where did all the energy go?

4a. A 100 kg roller coaster is pulled up to the top of its first hill from 0 meters to 50 meters.  What is the change in potential energy of the coaster?

4b.  At the top of the first hill, the coaster comes to a stop.  What is the kinetic energy of the coaster?

4c. At the bottom of the first hill, the coaster is going 31.6 m/s.  What is the kinetic energy of the coaster?

4d. What is the potential energy of the coaster at the bottom of the first hill?

4e. Where did all the potential energy in 4a go when the coaster reached the bottom of the hill?

Today you will learn all about the Conservation of energy by studying the motion of a skateboarder. For all the questions below, draw the pictures and write the answers on the handout.

1. Look up the definition of Kinetic Energy and Potential Energy (avoid the Wikipedia info please). Write the definitions in your notes.

2. Find the equations for calculating Kinetic energy and potential energy and write them in your notes. Be sure to include definitions for each variable in the equations.

Run the simulation linked here.

3. Click the box for the Measuring Tape, Potential Energy Reference and Show Grid. Drag the low point down ground and use the measuring tape to measure how high the skater rises.

4. Slow the simulation down by dragging the sim speed control toward slow and then click the show path button. Why are the dots spread apart at the bottom of the ramp and are very close at the top? What do the dots tell you about speed and acceleration?

5. Turn on the Energy vs. Position graph, draw it in your notes, then answer the following questions by pausing the simulation at the right time or just watching closely:

What is the total energy when the skateboarder is at the top left of the ramp, the middle, and the top right?

What is the potential energy at the left, middle, and top right?

What is the Kinetic Energy at the top left, middle, and top right?

6. Click Energy vs. Time. When the kinetic energy is greatest, what is the potential energy?

When the Potential energy is greatest, what is the kinetic energy?

Pause the simulation at any time and add the potential energy and the kinetic energy. What do you get? Play it again and pause it at a random place. Add the two again. Based on this, is energy conserved throughout the motion?

7. Turn on Track Friction and increase the coefficient of friction a little. Click the Return Skater button on top describe what happens to the skater when friction is present. Is energy conserved when friction is present?

8. Turn on the Energy vs. Time graph and re-run the simulation with friction on. Draw the graph in your notes and label the total, thermal (heat), Potential, and Kinetic Energy.

What happens to the potential and kinetic energies? Where does the energy go? Is energy conserved? Why or why not?

9. Add some track to make your skateboarder ride on a roller coaster (loops work!). Draw your track. Drag the skater to the beginning of the track and let him ride. It will work better if you turn friction off.

10. See how your roller coaster works in space by clicking the Location = Space box. Describe what happens.

Today you will create an Impulse Presentation using Keynote.  Remember it is in the iWork folder.

For each slide of your presentation, do all of the following on each slide.

1. Find an image of it happening.

2. Explain what is causing the impulse.

3. Explain how the momentum of the object is changing.

4. Explain if it is a large force for a short time or a small force for a long time.

Here are the slides you need:

Slide 1: Title and Names

Slide 2. A ball being kicked

Slide 3. A ball being thrown.

Slide 4. A car crashing into a wall.

Slide 5. A dragster slowing down with a parachute.

Slide 6. A rocket blasting off.

Slide 7. A punch.

Slide 8. A billiards break.

Slide 9. An asteroid impact.

Slide 10. A football Hit (one player running into the other)

Slide 11. A lay-up

Today on the Knowledge Grid:

 I know an unbalanced force on an object produces a change in its momentum.

Put the word Impulse in the notes section of the Knowledge Grid along with the equation Ft = Δp

1. Video about impulse.

2. Example problems using impulse

3. Impulse problems.

Impulse Problems Page____

Calculating Impulse

1. A model rocket engine exerts a force of 10 newtons for 3 seconds. What is the impulse applied to the rocket? (Impulse = Ft)

2. A car engine applies a force of 10000N for 5 seconds. What is the impulse applied by the engine? (Impulse = Ft)

3. When you hit a baseball with a bat, the bat applies a force of about 18,000N for 0.0007 seconds. What impulse does the bat apply to the baseball? (Impulse = Ft)

4. A pitched baseball (0.15kg) travels at a speed of 40 m/s across the plate (90 mph). Calculate its momentum. If it leaves the bat with the same momentum but in the other direction, what is the impulse on the ball? (Impulse = ∆p)

5. When your head hits the ground after falling down, it is moving at about 2 m/s. What is the impulse applied to your head If your head has a mass of 5 kg? (Impulse = ∆p)

Using Impulse Momentum Equation

6. A model rocket engine exerts a force of 10 newtons for 3 seconds. If the rockets starts with zero momentum, how much momentum does it have after the engine shuts off (Ft = ∆p)?

7. If the rocket in #5 has a mass of 0.1kg, how fast is it moving after the engine shuts off (p =mv)?

8. When your head hits the ground after falling down, it is moving at about 2 m/s. If your head has a mass of 5 kg, how much momentum does your head have when it hits (p = mv)?

9. If your head comes to complete stop after hitting the ground, what is the change in momentum of your head (∆p = p_f – p_i).

10. If your head comes to a stop in a time of 0.001 seconds, what is the force exerted on your head
(Ft = ∆p)?

11. If instead of hitting the ground, you hit a foam matress and it takes 0.1 seconds for your head to come to a stop. How much force is exerted on your head (Ft = ∆p)?

12. If instead of hitting the ground, you hit water and it takes 2 seconds for your head to come to a stop. How much force is exerted on your head (Ft = ∆p)?