ENERGY & POWER
Energy = the ability to do work. Work and Energy:are related, we give energy to an object by doing work on the object. Measuring Energy: Because work is the transfer of energy, we can measure energy by measuring the work done.
For example if a boat does 5,000 Newton’s of work, the engine of the boat put out 5,000 N-m’s of energy. One Newton meter is = to a Joule (J) So to find out how much energy is needed to do something we use the formula for work.
Kinetic Energy: is the energy of motion. If you stop a moving object you can feel it’s Kinetic Energy. Kinetic Energy depends on two things. Mass & Speed of the object. More Kinetic Energy 100km/hr 100km/hr
Calculating Kinetic Energy: KE=1/2mv2 answer is in Joules. mass velocity Example: A girl has a mass of 40 kg skates around a rink at 12m/s. What is her Kinetic energy?
A boy has a mass of 120 kg runs at a speed of 4 m/s. What is his KE? A man has a mass of 100 kg walks at a speed of 2 m/s. What is his KE?
3. A baseball with a mass of 0. 08 kg is thrown at a speed of 20 m/s 3. A baseball with a mass of 0.08 kg is thrown at a speed of 20 m/s. What is the KE of the baseball? 4. A soccer ball with a mass of 2 kg is kicked at a speed of 5 m/s. What is the KE of the soccer ball?
Potential Energy: Is energy due to an objects position. Calculating Potential Energy: Is work done or Force X Distance = Joules Example: If a boy carries a 70 n bowling ball up a flight of 20 m high stairs. What is the balling ball PE? Answer: 70 n X 20 m = 1400 J
Law of Conservation of Energy: States that energy cannot be created or destroyed. It can change from one form to another. But the total amount of energy remains the same. {EXCEPT SOME IS LOST DUE TO FRICTION}
Friction Wastes Energy: The lower the friction the less energy wasted. The less energy wasted the faster you go. The less energy wasted the more PE converted to KE. PE PE & KE PE if Stopped
Forms of Energy Mechanical: energy an object has from its motion. Internal: energy from all the particles of an object. Electrical: electricity
Chemical: energy from an objects position and its form of PE. Radiant: energy in the form of a wave the sun Nuclear: energy released from splitting or combining atoms.
Power: is the rate at which work is done. Power = work/time it’s the rate at which energy is used. Example: If a person used 1200 J’s of energy in 10 minutes how much power does that person have? Answer: 1200 J / 10 minutes = 120 J/m Some times we convert minutes to seconds for example 10 minutes = 600 seconds.10 X 60. 1 Joule per second is equal to a watt (W) Power is measured in watts.
1- Chemical Energy: Energy from an objects position. (Potential Energy) 2- Electrical Energy: Energy that flows through a wire (Kinetic Energy) 3- Energy: The ability to do work. 4- Internal Energy: Energy to the particles that make it up. 5- Joule: Metric Unit for energy.
6- Kinetic Energy: Energy because the object is moving. 7- Law of Conservation of Energy: Energy cannot be created or destroyed. Energy changes from on form to another. 8- Mechanical Energy: Energy an object has from its motion. 9- Nuclear Energy: Form of Potential energy the splitting of atoms
10- Potential Energy: Energy due to an objects position 10- Potential Energy: Energy due to an objects position. We give objects energy by doing work on them. 11- Power: The rate at which work is done. 12- Radiant Energy: Energy from the sun in the form of a wave. 13- Watt: Metric unit for power.
14-If the rock's potential energy is100 J, the hill is _________ high. 15-At point C, the rock's potential energy will be __________ . B 16-The rock's kinetic energy at point A is __________. C 17-At point B, some of the rock's potential energy will be changed to. ________________________________ 18-The rock's potential energy at point A is __________ than it's kinetic energy.