Question

A 0.75 kg model car is moving west at a speed of 9.0 m/s when it collides head-on with a 2.00 kg model truck that is traveling east at a speed of 10.0 m/s. After the collision, the 0.75 kg model car is now moving east at 11 m/s. What is the speed and direction of the model truck after the collision?



a.
9.3 m/s east
c.
2.5 m/s east
b.
9.3 m/s west
d.
2.5 m/s west

Answer 1

@Mashy

Answer 2

lol that was fast x D

Answer 3

I got B by the way!

Answer 4

I'm skilled in the art of the computer XD

Answer 5

you mean CTRL C, CTRL V? XD

Answer 6

Yessum! XD

Answer 7

last question until i start my new pre-test by the way :D

Answer 8

ok wait lmme check!

Answer 9

wait it would be going west instead of east so i change my answer to the 2.5 West D.

Answer 10

ok..

consider EAST as +ve.. and West as -ve

tell me what is the total intial momentum?

Answer 11

quick.. i need to take bath.. i stink o.O

Answer 12

26.75?

Answer 13

And LOL

Answer 14

how did you get that?

remember EAST is positve.. so the 2kg truck momentum is +ve..
and WEST is negative.. so the 0.75 kg truck momentum is -ve.. so try again!

Answer 15

oh yes. I forgot. I just remember that you take the weight x meterpersecond.

Answer 16

so i just put a negative for the one that travels west? then add?

Answer 17

yes !

Answer 18

okay now i have 13.25

Answer 19

wait i think i messed up again XD

Answer 20

and its positive.. so the total initial momentum is towards EAST.. (that is not so hard to understand because the truck as more momentum)
so definitely the final momentum should also be +13.25

Answer 21

so let the trucks final momentum be x (cause u dunno lol)
the model cars momentum is gonna be +ve .. (cause its going east) ...
so now make an equation and find x

Answer 22

OOOOOH! Okay! That makes a whole lot more sense than trying to google all of this stuff XD

Answer 23

so it would be x = 13.25?

Answer 24

Wait how would i set up the equation?

Answer 25

no.. total final momentum = x + final momentum of the car

Answer 26

ahhh, What is the first step to finding?

Answer 27

This is where i get really confused. The brain using part XD

Answer 28

momentum = mass times velocity

so tell me what is the final momentum of the car??

Answer 29

Which one of those do i already have of? is 13.25 my velocity? or?

Answer 30

or is that my initial momentum?

Answer 31

13.25 is the total initial momentum

:O

the car after collison goes with 11 m/s EAST.. so what momentum does it have now after the collision?

Answer 32

145.75? since it moves east?

Answer 33

HOW CAN IT BE 145.75???

MASS = 0.75

VELOCITY = 11..

what do you get when you multiply them!?

Answer 34

Lol I am totally multiplying the wrong mass XD

Answer 35

i thought i used what i got for the initial. I didn't realize i had to use the original mass.

Answer 36

8.25 now Lol.

Answer 37

you need to learn concept and do more problems and stop googling O.O

Answer 38

Well i would love to learn how to do it. I just take tests after tests. No lessons in between.

Answer 39

And there isn't anybody around to help me out in person.

Answer 40

so conservation of momentum says

total initial momentum = total final momentum

13.25 = x + 8.25

Answer 41

Divide each side by 13.25?

Answer 42

that yields x = 5.. which means the truck is gonna go EAST..

so trust finally momentum =+ 5 kgm/s

Answer 43

omg .. you need to learn ALGEBRA!!

Answer 44

It's been 3 years XD

Answer 45

SO what is the answer gonna be? 5 is neither of my choices XD

Answer 46

or was I right in the first place with B? XD

Answer 47

my bad
C

Answer 48

yes C