What is the Linear Impulse of a Potato with Changing Speed?

[lokobreed]

Homework Statement

A 0.30 kg potato speed changes from 6.0 m/s to 2.0 m/s. What is the linear impulse of the potato

Homework Equations

The Attempt at a Solution

mv(final) - mv(initial)
.3 * 2-.3 * 6 =

This gives me the change but after that I am lost... any help?

 

[tiny-tim]

hi lokobreed!

What is the linear impulse of the potato
…
mv(final) - mv(initial)
.3 * 2-.3 * 6 =

This gives me the change but after that I am lost... any help?

but that's it!

(linear) impulse is total change in (linear) momentum, so just say what the units are, and you're done!

 

[lokobreed]

so the above question and this "A 0.30 kg potato speed changes from 6.0 m/s to 2.0 m/s. What is the change in momentum of the potato" mean the same thing?

for this question i got 1.2 kg m/s from subtracting mv(i) from mv (f), but i thought that this was just for the change in momentum and linear impulse (the above question) meant something else...

 

[tiny-tim]

no, force = rate of change of momentum,

and impulse = ∫ force*time = total change of momentum

 

[lokobreed]

Tim thank you very much for your help. Could you just clarify what you said please.

1) A 0.30 kg potato speed changes from 6.0 m/s to 2.0 m/s. What is the change in momentum of the potato - this is mv(f) - mv(i) ?


2) A 0.30 kg potato speed changes from 6.0 m/s to 2.0 m/s. What is the linear impulse of the potato - this is force*time = total change of momentum ?

or am i wrong?

 

[lokobreed]

I still don't see how to formulate the linear impulse if I am doing the change of momentum problem correctly.

 

[ideasrule]

I don't understand your difficulty. Impulse is the change in momentum. tiny tim was showing you why the two definitions of impulse--namely, the integral of F*dt and mv_f-mv_i--are actually equivalent.