 A weightlifter lifts a 45 kg barbell 0.65 m. If it takes 280 W to move the barbell, how many seconds did it take?

 Includes momentum (including conservation) and impulse  14 multiple choice questions ◦ Choose the 1 best answer  2 multiple select questions ◦ Choose exactly 2 options  Some questions may be extra credit

Chapter 11

 Energy is the ability of an object to change itself, other objects, or the world around it.  Itself: Energy can be changed from one form to another  Other objects: Energy can be transferred from one object to another, often through collisions  Surroundings: Energy can be transferred (such as heat) to surroundings

 Kinetic  Potential ◦ Gravitational ◦ Elastic ◦ Electrical ◦ Chemical ◦ Mass

 The SI unit of energy is the Joule (J)  This is the same unit as work

 Kinetic energy is the energy an object has due to its motion

 Calculate the kinetic energy of a kg baseball traveling at 40.0 m/s

 Calculate the kinetic energy of a 1100 kg car backing up at 1.5 m/s.

 The net work done on an object is equal to the object’s change in kinetic energy

 A hockey player hits a 0.16 kg puck with a force of 120 N for a distance of 0.92 m along frictionless ice. If before the slapshot the puck was moving forward at 1.4 m/s, what was the puck’s speed after the shot?

 A soccer player is running towards a 0.43 kg soccer ball that is moving towards the goal at 0.76 m/s. When she reaches the ball, she kicks it with a force of 110 N for a distance of 0.43 m. What is the ball’s speed after the kick? Ignore friction.

 A collision is called elastic if kinetic energy is conserved  A collision is called inelastic if kinetic energy is not conserved  A collision is called perfectly inelastic if the two objects have the same final velocity (stuck together)  Momentum is always conserved in a closed, isolated system.

 Earth’s gravity pulls on a 13 kg rock as it falls from rest off of a cliff. Use the work-energy theorem to find the rock’s velocity after it has traveled 15 meters.

 Earth’s gravity pulls on a 50.0 kg rock as it falls from rest off of a cliff. Use the work- energy theorem to find the rock’s velocity after it has traveled 15.0 meters.

 Calculate the potential energy of a 18 kg child at the top of a 2.5 m tall slide, relative to the ground below.

 A 75 kg boulder is resting precariously at the edge of a cliff that is 32 m above the ground below. What is the potential energy of the rock, relative to the ground below?

 An airplane with mass of 3.7x10 5 kg is flying with a velocity of 89.0 m/s at an altitude of 3.1 km. What is the potential energy of the airplane, relative to the ground below?

 A 7.8x10 3 kg car is at the top of a hill. It drives down the hill where the elevation is lower by 23 m. If the top of the hill is the reference level, what is the car’s potential energy at the bottom of the hill?

 A 1.3 kg ball is thrown horizontally with a velocity of 4.2 m/s at a height of 1.9 m.  Calculate the ball’s kinetic energy  Calculate the ball’s gravitational potential energy

 Energy is conserved (always)  Since energy can be converted between its different forms, it is the sum of energy types that is conserved.  If no work (other than gravity) is done to a system:

 A kg baseball is thrown vertically from a height of 1.3 m with a velocity of 5.2 m/s. Assume air resistance is negligible. a) What is the maximum height of the baseball? b) What is the baseball’s velocity 2.4 m above the ground?

 Stanley (one of Mr. Szwast’s nephews) slides down a frictionless slide. The top of the slide is 2.4 m above the ground. The bottom of the slide is 0.3 m above the ground. If Stanley pushes off to give himself an initial speed of 0.5 m/s, what is Stanley’s speed at the bottom of the slide?

 A 1200 kg car is parked at the top of an icy hill. Its brakes fail, and it begins to slide down the hill. At the bottom of the hill, the car is traveling 7.1 m/s. What is the height of the hill?

 Everything from last time, plus: ◦ Momentum ◦ Impulse ◦ Work ◦ Power ◦ Kinetic Energy ◦ Potential Energy

 Potential Energy  Kinetic Energy  Conservation of Energy  You have the rest of class to work on these worksheets with your partner.

 Clear everything off of your desk except: ◦ Pencils (bubble sheet must be done in pencil) ◦ Erasers ◦ Pens (if you want to do your work in pen) ◦ Scientific calculator ◦ Green reference sheet  Make sure your cell phone is powered off and in your backpack (not your pocket)

 40 minute time limit  Bubble in your version number.  Do all of your work on the test.  If you appear to be talking, looking at another student’s test, allowing another student to look at your test, or using any unauthorized aide, you will receive a zero.  If your cell phone is seen or heard, it goes to the office and you get a zero.  When finished turn in your quiz and bubble sheet and work on the worksheets due Monday.  Quizzes will be graded by lunch. You may come during lunch to see what you missed.

 Potential Energy  Kinetic Energy  Conservation of Energy  You have the rest of class to work on these worksheets with your partner.

 A cannon shoots a 5.4 kg cannonball straight up at 95 m/s. This was a very bad decision, as the cannon was inside a building at the time. How fast is the cannonball traveling when it hits the ceiling 2.1 m above the cannon?

#Ver. 1Ver. 2 1AAD 2BBD 3DA 4EE 5EC 6AE 7CE 8DA #Ver. 1Ver. 2 9CC 10AA 11DD 12CB 13EB 14BD 15ADD 16BDC

 Top Thrill Dragster is one of the tallest, fastest roller coasters in the world. It shoots passengers out at 120 mph (53.6 m/s) up a track to a height of 420 ft (128 m). What is the velocity of the roller coaster at the top of the track? Ignore friction and air resistance.

 A raindrop falls from a rain cloud m above sea level. How fast is it moving just before it hits the ground if the elevation of the ground is 89m?  What is wrong with this problem?

 A 1250 kg rocket is launched with an initial velocity of 13 m/s. What is the maximum height that the rocket can reach?  What is wrong with this question?

 A 2.00 kg black ball is rolling east at 3.00 m/s. A 5.00 kg gold ball is rolling west at 2.00 m/s. If the collision is elastic, what is the final velocity of each ball?

 Check solutions to the worksheets: ◦ Potential Energy ◦ Kinetic Energy ◦ Conservation of Energy  Read Chapter 11  Page 306 #29, 32-36, 47-50, 53 – Due Wed/Th  Page 309 #84-94 – Due Friday

 An astronaut hits a golf ball on the moon. The golf tee is m above the ground. The golf ball leaves the tee at 17.9 m/s. The ball hits the side of the lunar lander 4.43 m above the ground with a speed of 17.5 m/s. What is the acceleration due to gravity (g) at the surface of the moon?

 A 2.00 kg black ball is rolling east at 3.00 m/s. A 5.00 kg gold ball is rolling west at 2.00 m/s. If the collision is elastic, what is the final velocity of each ball?

 When a particular spring is compressed m, it has 28.9 J of potential energy. What is the spring constant of this spring?

 Check solutions to the worksheets: ◦ Potential Energy ◦ Kinetic Energy ◦ Conservation of Energy  Read Chapter 11  Page 306 #29, 32-36, 47-50, 53 – Due Wed/Th  Page 309 #84-94 – Due Friday

 A 2.1 kg rock is thrown horizontally with a velocity of 7.2 m/s at a height of 1.8 m.  Calculate the ball’s kinetic energy  Calculate the ball’s gravitational potential energy

 No notes, no calculator, no reference sheet  6 minute time limit  Turn your quiz over when you are finished.  Mr. Szwast will collect all quizzes after the 6 minute time limit.

 Potential Energy & Kinetic Energy – Wednesday  Conservation of Energy – Wednesday ◦ Typo on #3: v i = 5.10 m/s (not 2.10)  Momentum and Energy Review – Friday  Momentum and Energy Crossword – Friday

 An astronaut hits a golf ball on the moon. The golf tee is m above the ground. The golf ball leaves the tee at 17.9 m/s. The ball hits the side of the lunar lander 4.43 m above the ground with a speed of 17.5 m/s. What is the acceleration due to gravity (g) at the surface of the moon?

 Monday 10 th – Elastic and inelastic collisions  Tuesday 11 th – Review  Wednesday 12 th – Review  Thursday 13 th – Benchmark #2 (graphs)  Tuesday 18 th – Review worksheet  Wednesday 19 th (minimum day) – Review  Thursday 20 th (sub) – Test on momentum and energy  Week of 24 th – Review for and take final exam

 A collision is called elastic if kinetic energy is conserved  A collision is called inelastic if kinetic energy is not conserved  A collision is called perfectly inelastic if the two objects have the same final velocity (stuck together)  Momentum is always conserved in a closed, isolated system.

 This packet is due Thursday.  Mr. Szwast will answer questions before we take a quiz on the material.