Understanding Kinetic and Gravitational Potential Energy Through Projectile Motion

good morning today we're going to investigate energy specifically we'll be looking at

kinetic energy gravitational potential energy and total energy so i'm just going to launch this

projectile upwards and let's see what happens so there's three columns there notice

that total energy stays constant let's launch it again total energy does not change

this is because in this simulation right now we've removed air resistance and so when there's no

air resistance the total energy stays the same please pay careful attention to gpe

gp is gravitational potential energy notice that gravitational potential energy

is at a maximum when the height of the object is at a maximum notice that gpe gravitational potential

energy is zero when the object is at a height of

zero finally let's pay attention to kinetic energy ke

kinetic energy is zero when the object is at peak height why is that well because at peak height

the object is stationary so when is kinetic energy a maximum well kinetic energy is a maximum

when the object's moving the fastest let's now take a look when we launch this object at an angle of 45 degrees

again total energy doesn't change it's the sum of kinetic and potential but notice this time that kinetic energy

does not go to zero at peak height right around here the object still has speed

let's see that again so right around there the object still has speed

and as a result since the object still has speed it still has kinetic energy

again when is kinetic energy maximum when potential energy is at zero when the object is very close

to the ground and the object is moving at its highest speed when it's close to the ground

now let's look at it when we launch at a higher angle at 75 degree angle well notice this time kinetic energy

gets closer to zero but it's never actually equal to zero why is that

well at peak height it still has some speed again though notice that kinetic energy

plus gravitational potential energy equals total energy now this simulation allows us to

add drag or air resistance let's see what happens when we add some drag

here we go notice immediately what happens to total energy total energy has decreased by at least

50 percent why is that well the drag force is converting some of the energy

into heat notice that the peak height is significantly decreased why because some of the energy now has been lost due

to drag notice also that the distance is traveled has decreased

because some of that energy has been lost due to drag let's see the situation for a 45 degree

angle launch notice once again that the object doesn't travel as high

due to drag due to energy loss due to drag and again it doesn't travel as far

either due to drag so i hope you enjoyed this video

have a great day bye