U1 Energy Review

Energy is…

the ability to do work

Work is when…

a force is applied on an object to move a certain distance

Work is only done when…

an object is in motion

Work =

fd (force x distance)

The unit for work is…

nm (newton-meter)/joule

The nm is also known as…

joules

force is measured in — and distance is measured in —

newtons, meters

because work is part of energy, energy is also measured in…

joules

Power is …

the rate at which work is being done

someone who can get more work done in less time is (more/less) powerful

more

the formula for power is…

p = w/t

the unit for power is…

watts

kinetic energy is…

the energy of motion

kinetic energy depends on…

mass and speed, but speed makes a bigger difference (doubling speed would actually be quadrupling because its already squared)

the equation for kinetic energy is…

½ mv²

potential energy is…

the energy stored in an object due to its chemical composition, position, and condition

elastic potential energy is…

potential energy stored in an object that is compressed or stretched

chemical potential energy…

potential energy stored in the chemical bonds that make up certain compunds

gravitational potential energy…

potential energy stored in an object in relation to its height to the ground

when a swing moves down…

the gpe (from being at the highest point) is converted to ke

(when one goes up, the other goes down)

as the swing moves up the g.p.e — and the kinetic energy —

increases, decreases

describe energy transfers and transformations in a toy car

the chemical potential energy stored in the battery is transformed to electricity which flows through a wire which is transferred to various parts of the system

describe energy transfers and transformations in turning on a battery operated fan

the chemical potential energy in the battery is transformed to electricity which is sent to the propellers of the fan through the motor which is then transformed to kinetic energy.

examples of c.p.e

matches

gasoline

plants

food

battery

flashlight

examples of little kinetic energy

book on table

snail

anchor

turtle

slow soccer ball

person walking

examples of elastic potential energy

rubber band

bow and arrow

slingshot

spring

trampoline

examples of a lot kinetic energy

ball thrown in the air

chair falling

door swinging open

moving train

plane in sky

wrecking ball

rocket

examples of gravitational potential energy

a car on a hill

a person on a cliff

a pen on a table

skydiving

boulder on a mountain

force =

ma (mass/2.2 x acceleration)

where is pe on a roller coaster the greatest?

at the top

when is ke on a roller coaster the greatest?

at the bottom

what is one transformation when something is falling down from a height?

gpe to ke

what is an energy transformation?

an energy transformation is when one energy type transforms to another

what is an energy transfer?

an energy transfer is when one source of energy transforms to another location (same energy type)

types of ke

thermal, electromagnetic, sound, electrical

types of pe

elastic, chemical, gravitational, nuclear

what is the law of conservation of energy?

energy cannot be created or destroyed

what is a system?

parts working together to create a collective result. energy is not created or destroyed in a system. an example is plants working together for photosynthesis

what is the main component of most toys?

a circuit, it acts as the brain of a system

some energy in a system is always…

wasted due to friction of moving parts, which makes no machine efficient

when is the gpe the highest in a pendulum?

when the ball is at the highest point

when is kinetic energy in a pendulum the highest?

when the ball is at the bottom and about to swing back up again

transformations in a roller coaster

when the car is on its way down from the hill, the gpe is slowly being changed to kinetic. when it is at the complete bottom, kinetic energy is at its highest, which gives it energy to go upwards again. when it goes back up a hill the kinetic is changed to gpe

transformations in a pendulum

when the ball is it its highest point, gpe is the highest and kinetic energy is at its lowest. when it goes back up ke is transformed to gpe, and at the very bottom ke is at the maximum and gpe is minimal.