Do Now 10/29/14 5 minutes Take out Scratch Paper and Calculator for our Jeopardy Review Write down formulas PE = mgh, KE = ½mv2, TME = PE + KE Gravitational P.E= (1/2)kx2 Position One winner person EARNS 3 points of extra credit! Position Two earns 2 extra points, and third winner will choose 1 extra point. Only one i-pad should be used in the group of four, with scorer included.

Jeopardy Rules One common problem from the group will be selected and anyone who gets it first right, will score points and will choose the next category. If a person answers incorrectly or can’t explain the reasoning, next team person has chance to steal, then next time. BE PREPARED! First three Winning people will get extra points.

Jeopardy

Conservation of Energy Work PE KE Conservation of Energy 100 100 100 100 200 200 200 200 300 300 300 300 400 400 400 400 500 500 500 500

How do you determine when a force is doing POSITIVE or NEGATIVE work? Positive work if force is in the SAME direction as displacement. Negative work if force is in the OPPOSITE direction as displacement How do you determine when a force is doing POSITIVE or NEGATIVE work? Row 1, Col 1

height / increasing its height Gravitational Potential Energy of an object depends on its mass and __________. You can increase an object’s Potential Energy by __________________. Row1,Column2

An object only has Kinetic Energy if ______________________. the object is moving. An object only has Kinetic Energy if ______________________. 1,3

stays constant According to the Law of Conservation of Energy, the total amount of mechnical energy ___________. 1,4

F1 is doing zero work because it is perpendicular to motion. The object below is moving to the left. Which Force is doing zero work? F1 F2 2,1

7350 J A 75 kg man is on a ladder that is 20 m tall. What is his Potential Energy when he is halfway up the ladder? 2,2

TRUE – KE doesn’t depend on direction. Two cars of equal mass are traveling in opposite directions at the same speed. TRUE or FALSE – Both cars have EXACTLY the same amount of Kinetic Energy. 2,3

Remember that TME = PE + KE A diver of mass 50 kg freely falls from a diving board located 15 m from the water. Fill in the following table about the diver’s mechanical energy. 2,4 `` Height PE KE TME 15 m 7350 J 0 (at water) Height PE KE TME 15 m 7350 J 0 (at water)

If the object travels 20 m up, how much work is done by F1 and F2? W1 = 16000 J, W2 = -6000 J F1 = 800 N If the object travels 20 m up, how much work is done by F1 and F2? F2 = 300 N 3,1

PE = 40,000 J Spiderman weighs 1000 N. He climbs up the side of a building. What is his potential energy after climbing 40 m? 3,2

3,3 4 kg bowling ball (32 J) Which object has more Kinetic Energy? A 4 kg bowling ball traveling at 4 m/s Or An 8 kg bowling ball traveling at 2 m/s 3,3

PE = 3920 J, KE = 3920 J A sled of mass 20 kg is at rest at the top of a 40 m tall hill. Ignoring friction, how much Kinetic Energy and Potential Energy does the sled have when it is halfway down the hill? 3,4

Work done on object is -5000 J 3 Forces are acting on an object. F1 500 N to the left. F2 400 N to the right. F3 is 200 N to the right. If the object has a displacement of 50 m to the left, how much work was done on the object? 4,1

∆PE = PEf – PEi = -9800 J Tarzan climbs down a vine. If his mass is 200 kg, what is his change in potential energy when he climbs from 15 m to 10 m off the ground? 4,2

KE = 159,438.78 J A car of weight 5000 N is traveling at -25 m/s. How much Kinetic Energy does the car have? 4,3

PE = 24.5 J, KE = 85.75 J A coconut of mass 1.25 kg is attached at the top of a tree of height 9 m. When the coconut falls off, how much PE and KE will it have once it falls to a height of 2 m? 4,4

Work done on book is 117.6 J A 3 kg Physics textbook falls from a shelf that is 4 m from the ground. Find the work done on the textbook while falling from the shelf to the ground. 5,1

Potential Energy is the maximum amount of work that gravity can do to an object because work done by gravity of an object that has fallen is found by multiplying Fg by its height from the ground. Potential Energy is calculated the same way. Explain the relationship between gravitational Potential Energy and the work done by gravity on a falling object. 5,2

KE = 480 J, v = 34.6 m/s A baseball pitcher is throwing a baseball of mass 0.8 kg. After the pitcher applies a force of 120 N over a displacement of 4 m, How much KE does the baseball have? How fast is the baseball traveling? 5,3

speed at bottom of loop = 22.18 m/s A roller coaster cart is traveling 10 m/s at the top of a loop. If the loop is 20 m tall and the cart has a mass of 300 kg, how fast is the cart traveling at the bottom of the loop? 5,4