Question

A cart moving at 15 m/s is brought to a stop by the force plotted in the force–time graph attached inside. Find the impulse and the approximate mass of the cart. How would I show all the work for this?

Thank you:)

Answer 1

graph!

Answer 2

So the impulse (J) is the integral (the area) of that graph

Once you find J, then you can use \(J=\Delta P=mv_2-mv_1\)

where \(v_2=0\)

Answer 3

okay:) how do i know what to plug in for mv2 and mv1? i'm not quite sure about that :(

Answer 4

so it'd be like J=m(0)-mv1? not sure what the m is? Is that 15? and v1 would be 8? :/

Answer 5

@aaronq ? :)

Answer 6

sorry, the site takes forever to load sometimes.

m is mass, what you're looking for - so it's unknown until you solve the question

\(v_1\) is the initial velocity 15 m/s

Answer 7

okay! so i get this?

J=m*15m/s -m*0
J=15m

?

is that correct? If so, what happens now? @aaronq :)

Answer 8

I'm thinking you'd want the physics section
since you'd need the equation with the Force and Impulse

Answer 9

sorry, got laggy! :( ohh i have it listed on my subjects, but i can't enter it :/

Answer 10

sorry, the site has been weird for me!

so remember i said the impulse (J) is the area under the curve of the F vs time graph?

Find (estimate) the area of that graph you posted!

(ps. check where you substituted your values to that formula, they're not right)

Answer 11

ahh okay:) and no worries, it's been weird on my end too!

oh so would that mean J=9*25=225

and so 225=mv1-mv2
225=mv1-m(0)
225=mv1-0

225=m*15 ?

225/15=m

15=m ?

so the approximate mass is 15 (what would the units be again? :/)

and the impulse is 225 (would this be m/s?) ?

Answer 12

According to the graph, it looks like the horizontal side of the rectangle should be 8, not 9.

Answer 13

ohhh okay, so it should be J=8*25=200

and then 200/15=13.3333

so impulse is 200 and approximate mass is 13.33?

also, i'm not completely sure what units :/

Answer 14

I'm not entirely sure either. Your force axis is labeled (m), which suggests meters, but surely that's not what it should be. Maybe (N) for Newtons?

Answer 15

ohh okay:) yeah i didn't think meters could be appropriate for this, but I wasn't sure!

but the calculations above were correct then? impulse would be 200 and mass is 13.33?

Answer 16

Looks good to me

Answer 17

awesome, thank you!!