Chapter 4: Energy

transfer of energy

transfer of energy

Work is defined as the ________ when a force is applied to an object and causes it to move.

potential energy

The ________ associated with a conservative force can be calculated using the formula: PE=- Wc, where Wc is the work done by the conservative force and PE is the ________.

Conservative forces

________ are forces that do not dissipate energy and do not depend on the path taken by the object.

Power

________ is the rate at which work is done or energy is transferred.

Work can be calculated using the formula

W = F x d x cos(theta), where F is the force applied, d is the distance moved, and theta is the angle between the force and the displacement vectors

Power can be calculated using the formula

P = W/t, where W is the work done and t is the time taken

The work-energy theorem can be written as Wnet = KEf

KEi, where Wnet is the net work done, KEf is the final kinetic energy, and KEi is the initial kinetic energy

The potential energy associated with a conservative force can be calculated using the formula

PE = -Wc, where Wc is the work done by the conservative force and PE is the potential energy

pulling in two dimensions

no vertical work because no accomplishment/movement

when will work be negative

when a force is acting in the direction opposite to the direction of motion

area under the curve is work

area under the curve is work

the work done to lift something

you give an object precisely that much gravitational potential energy

pe grav equation

pe=mgh

pushing a crate horizontal

angle is 0 degrees cos 0=1

work to make something move

acceleration w=fd w=mad

if negative net work is done

body's kinetic energy decreases by an amount W net force exerted on a body opposite to the body's direction of motion reduces speed and kinetic energy

mass is doubled, kinetic energy is

doubled

if speed is doubled, kinetic energy is

4 times as much capable of doing 4 times as much work

kinetic energy of a group of objects

sum of kinetic energies of individual objects

hooke's law equation

f=kx

net work in relation to kinetic energy

=1/2 mvinitial squared-1/2 mvfinal squared equals change in kinetic energy

forces for which work done does not depend on path taken but on initial and final positions

conservative forces gravity

roller-coaster

assuming no energy work done getting car up=potential gravitational energy at the top=kinetic energy at bottom

energy losses

multiply loss by height before subtracting because loss is in n/m