Answer the following questions. Discuss with your elbow partner 1. What does the word “energy” mean to you? 2. What types of energy do you think exist in the universe?

New Unit! 1/26/22

 Hold an individual conference with me outside of class  Worth a lab grade of extra credit  If you are interested pick up a pre-conference form from me and sign up on my door

 Energy:the capacity of a physical system to change or perform work. work  All energy is either potential or kinetic: ◦ Potential: stored ◦ Kinetic: energy of motion

 Mechanical: The energy acquired by the objects upon which work is done; can be kinetic or potential  Ex: moving water; a rolling object

 Chemical: The energy stored by chemical reactions; potential  Ex: food, batteries

 Thermal: created by heat.  The hotter an object becomes the more thermal energy it possesses.

 Electromagnetic: produced when something upsets the balancing force between electrons and protons in atoms;  can be kinetic or potential

 Nuclear: energy locked in the nucleus of the atom.  Nuclear power plants split atoms in a process called fission

 Solar: energy from the sun

 Radiant (Light): waves that emit energy.  Ex: radio and television waves, gamma rays, and x- rays and sound

 Gravitational Energy - energy stored as a result of gravitational forces concentrated by the earth for the object.  Ex. Water held back by a dam

Work in groups to identify the types of energy in each example on the pink worksheet. Please have the worksheet completed by 10 minutes before the end of class. There may be more than one type of energy in each!

Work in groups to identify the types of energy in each example. There may be more than one in each! 1. Eating an orange 2. Charging your phone 3. Using solar panels to create electricity 4. A waterfall 5. Playing a PSP 6. Lighting a match 7. Shoveling snow 8. Skydiving 9. Using wind to create electricity

Identify the types of energy in each example. There may be more than one in each! 1. Charging your phone 2. A waterfall 3. Shoveling snow 4. Skydiving 5. Using wind to create electricity

 Work: a force exerted over a distance W=Fd Measured in Nm or joules (j)

1. A person pushing a wheelbarrow 5 m 2. A person pushing a wall that doesn’t move 3. A car traveling from Baltimore to New York 4. A book sitting on a table 5. Something being dropped from 15 m 6. A car moving at constant speed for 10 miles

KE= ½ mv 2  Measured in joules (j)

W=∆KE Fd= ½ mv f 2 - ½ mv i 2 W= ½ mv f 2 - ½ mv i 2 Fd=∆KE

1. A force of 15 N is required to push an object a distance of 3 m. a.What is the work done? b.What is the change in kinetic energy? 2. A 20 kg dog can run at 15 m/s. What is its kinetic energy?

 Use the rest of class to work on the paper: “Work and Energy.”

1. A force of 25 N is required to push an object a distance of 4 m. a.What is the work done? b.What is the change in kinetic energy? 2. A 15 kg dog can run at 8 m/s. What is its kinetic energy?

 A 20 kg mouse runs at 2 m/s then sees a piece of cheese and stops. What is the work done by the mouse to stop?

1. A 20 kg mouse runs at 2 m/s then sees a cat and starts running faster at 4 m/s. A.What is the work done? B.If the mouse speeds up over 4 m, what is the force required for the mouse to speed up?

 Please work on the pink sheet “Work and Energy.” It is due on MONDAY, but if you complete it by the end of class, you can receive EXTRA CREDIT!!!

1. A 20 kg mouse runs at 1 m/s then sees a cat and starts running faster at 3 m/s. A.What is the work done? B.If the mouse speeds up over 5 m, what is the force required for the mouse to speed up?

represented by either PE or U U g =mgh Where: m=mass g=acceleration due to gravity ( on earth 9.8 m/s 2 ) h=height or distance from the reference level Reference level: the position where the PE is determined to be zero

Determine the potential energy of a 2 kg ball on a cliff if the cliff rises 50 m above the ground.

Determine the potential energy of the same 2 kg ball once it drops to 20 m.

 Rate of change of work or energy of a system:  Power=work/time; measured in Watts (W)  1 W = 1 j/s

100 j of work are exerted for 12 s. 1. What is the power? 2. What is the change in kinetic energy?

 Use the rest of class to work on the paper “Power and Potential Energy.” It is due on Wednesday, when you will also have a QUIZ.

1. Determine the potential energy of a 0.5 kg ball on a cliff if the cliff rises 30 m above the ground. 2. Another object uses 68 j of work and takes 2 s to fall. What was its power?

 Work is a MAXIMUM at 0˚ and a minimum at 90˚

 You will have 25 minutes to complete the classwork. Use your textbook – page numbers with information are included on your worksheet.

 A force of 56 N is applied to a box at an angle of 41˚. If the box moves a distance of 0.23 m, what is the work done on the box?

Identify the types of energy in each example. There may be more than one in each! 1. Charging your phone 2. Shoveling snow 3. Skydiving 4. Using wind to create electricity

 Use the rest of class to work on your Exam Review Packet. It is due THURSDAY JUNE 2  If you need any notes or slides, please let me know  Today, please focus on the Unit 1 review: Work, Energy, and Power