ShmoopTube

00:00

Thank you We sneak And here's your shmoop too sure

00:06

brought to you by the wild west when we were

00:08

little we love to pretend that we were a cowboy

00:10

in the wild west Then we learned that it's a

00:12

bad idea to try to lasso a cat We learned

00:15

the hard way that one's pretty all right A rubber

00:18

bullet is fired at a wooden block and bounces the

00:20

block moves forward Ex meters bounces against the wall and

00:24

then slides before stopping at what point or points in

00:28

this situation is energy lost in any form Select two

00:32

answers on hearing the option was wondering how you think

00:35

Think about bullets and blocks All right well first of

00:38

all what did the block do to anyone who just

00:40

sitting there minding its own business When out of nowhere

00:42

ouimet gets a rubber bullet shot at it and goes

00:44

bouncing all over the place Hey did someone say bouncing

00:47

what That reminds us of an elastic collision Yeah Pretty

00:50

smooth segue way huh Well any lasted collision occurs when

00:54

an object bounces office Um and kinetic energy is conserved

00:58

And that means an inn elastic collision occurs when an

01:01

object collides with something And sticks they're losing kinetic energy

01:05

So for this question were looking at when kinetic energy

01:08

is lost The first time kinetic energy is lost happens

01:12

right away when the bullets fired When the bullet is

01:14

fired the bullet goes one way and unequal force has

01:17

to act on the gun in the opposite direction right

01:20

Newton after all his third law states that for every

01:23

action there's an equal and opposite reaction but the shooter

01:27

absorbs the recoil of the gun so kinetic energy is

01:30

lost at that point So answer d is one of

01:32

the right choices and after the bullets fired it hits

01:35

the block and bounces off Well that bouncing tells us

01:38

that we're dealing with an elastic collision this time And

01:42

as we know elastic collisions maintain kinetic energy Don't answer

01:46

b it's not one of the correct ones Then the

01:49

block hits the wall and bounces off that and yeah

01:52

there's more bouncing going on here than in a kangaroo

01:54

comic con answer a the word balances right innit That's

01:58

definitely wrong Then the block slides on the ground in

02:01

comes to a stop As the block slides kinetic energy

02:05

is transferred into heat energy from yes friction And besides

02:10

anytime something stops moving we can be pretty sure kinetic

02:13

energy is being lost So answer c which is our

02:16

other correct choice Remember we talked about kinetic energy being

02:20

lost but it doesn't go away It just changes to

02:23

other forms like magic and also remember that pets aren't 00:02:26.82 --> [endTime] always the best playmates Yeah maybe stick with legos

Full Transcript