Chapter 4 Energy

What is energy? Def: ability to cause _________________ Def: ability to cause _________________ Every change involves _______________________ Every change involves _______________________

Different Forms _________________________ _________________________ _______________________ – stored in food, involved in reactions _______________________ – stored in food, involved in reactions _______________________– gives off _______________________– gives off _______________________ – heat _______________________ – heat Same thing just different forms Same thing just different forms

Kinetic Energy Def: energy of a __________________ object Def: energy of a __________________ object Depends on _________________ and _________________ Depends on _________________ and _________________ Kinetic energy (Joules) = 1 mass (kg) x [speed (m/s)] 2 Kinetic energy (Joules) = 1 mass (kg) x [speed (m/s)] 2 2 KE = 1 mv 2 KE = 1 mv 2 2 SI unit for energy is ______________________ SI unit for energy is ______________________

Practice! What is the kinetic energy of a.15 kg baseball moving at 40 m/s. What is the kinetic energy of a.15 kg baseball moving at 40 m/s. A car moving at a speed of 20 m/s has a kinetic energy of 300,000 J. What is the car’s mass? A car moving at a speed of 20 m/s has a kinetic energy of 300,000 J. What is the car’s mass?

Potential Energy Even ______________________ objects have energy Even ______________________ objects have energy _____________________ in the object, has potential to change _____________________ in the object, has potential to change Def: ________________ energy Def: ________________ energy

Elastic Potential Energy Def: ___________________ energy by something that can _________________ or compress Def: ___________________ energy by something that can _________________ or compress Stretched rubber band – elastic potential energy  _________________ energy Stretched rubber band – elastic potential energy  _________________ energy

Chemical Potential Energy Def: energy stored in _____________________ bonds Def: energy stored in _____________________ bonds Food, gasoline, etc. Food, gasoline, etc.

Gravitational Potential Energy Def: stored energy by objects due to position ___________________ earth (able to fall) Def: stored energy by objects due to position ___________________ earth (able to fall)

Practice! Find the height of a.15 kg baseball that has a GPE of 73.5 J. Find the height of a.15 kg baseball that has a GPE of 73.5 J. Find the GPE of a.3 kg coffee mug on a 1-m high counter. Find the GPE of a.3 kg coffee mug on a 1-m high counter. What could you do to change GPE? What could you do to change GPE? Change _______________ or __________ Change _______________ or __________

Section 2 Conservation of Energy

Changing Forms of Energy Changing electrical energy –> electricity –> light and heat energy Changing electrical energy –> electricity –> light and heat energy Energy is ______________________ changing forms Energy is ______________________ changing forms

Transforming Chemical Energy Cars – ______________________ energy transformations Cars – ______________________ energy transformations Spark plug – ____________________ – engine - wheels Spark plug – ____________________ – engine - wheels

Transforming Chemical Energy _________________ plants – take in _________________ plants – take in _____________________ and transform to chemical energy in plants _____________________ and transform to chemical energy in plants

Mechanical Energy Def: total amount of ________________ Def: total amount of ________________ and ______________________ energy and ______________________ energy Mechanical Energy = Potential + Kinetic

Falling Objects As potential  kinetic, __________________ energy stays same As potential  kinetic, __________________ energy stays same Potential _________ = Potential _________ = kinetic _____________ kinetic _____________

Projectile Motion Mechanical energy remains _________________ Mechanical energy remains _________________ Still see _________________________ of energy Still see _________________________ of energy

Swinging Best part is falling from highest point Best part is falling from highest point High GPE = Low KE High GPE = Low KE Describe transition… Describe transition…

Law of Conservation of Energy Def: ___________________ can not be created or destroyed Def: ___________________ can not be created or destroyed Energy just changes _________________ Energy just changes _________________ All energy in the ________________________ does not change All energy in the ________________________ does not change Energy in = Energy out Energy in = Energy out

Is energy always conserved? Swinging – you eventually will stop – where does all the energy go? Swinging – you eventually will stop – where does all the energy go? ____________________ – air resistance = thermal energy ____________________ – air resistance = thermal energy

Human Body – Energy Relations What forms of energy are in your body? What forms of energy are in your body? Conservation of energy still true Conservation of energy still true Food, fat = __________________ energy Food, fat = __________________ energy Activity = ___________________ energy Activity = ___________________ energy Calorie 1C = 4,184 J Calorie 1C = 4,184 J

Chapter 6 Section 1 Temperature and Heat

Matter in Motion ______________________ is made of tiny ______________________ is made of tiny particles in _______________________ motion  have kinetic energy particles in _______________________ motion  have kinetic energy Faster = ________________ kinetic energy Faster = ________________ kinetic energy

Temperature Def: measure of ________________ kinetic energy of particles Def: measure of ________________ kinetic energy of particles High Temp. = ______________ Energy High Temp. = ______________ Energy Low Temp. = _______________ Energy Low Temp. = _______________ Energy Unit  Kelvin Unit  Kelvin

Thermal Energy _____________________ between air and butter particles increase energy of butter = ____________________ temperature _____________________ between air and butter particles increase energy of butter = ____________________ temperature Def: ________________ of kinetic and potential energy of particles in object Def: ________________ of kinetic and potential energy of particles in object

Thermal Energy As temp ___________________ = thermal energy increases As temp ___________________ = thermal energy increases If object has MORE __________________ and at the same temp. has HIGHER thermal energy If object has MORE __________________ and at the same temp. has HIGHER thermal energy

Heat Is your seat toasty? Is your seat toasty? Def: ________________ energy that flows from something at a _________________ temp to a lower temp Def: ________________ energy that flows from something at a _________________ temp to a lower temp Unit: Joule Unit: Joule

Beachin’ it up! How can there be extreme differences in temperature from air, _______________ and water? How can there be extreme differences in temperature from air, _______________ and water? Sun rays are the same why different temp? Sun rays are the same why different temp? Sand heats up ______ times faster than water Sand heats up ______ times faster than water

Specific Heat Specific Heat: heat needed to raise ___________ of material by 1  C Specific Heat: heat needed to raise ___________ of material by 1  C

Water as a Coolant It’s _______________ specific heat – absorb a It’s _______________ specific heat – absorb a lot of heat ________________ changing temp much lot of heat ________________ changing temp much ______________ bonds have to be broken before particles move really fast ______________ bonds have to be broken before particles move really fast