Solving Impulse Graph Questions: Velocity Calculation & Solution Check

[Nitrate]

Homework Statement

Homework Equations

fnet(delta t) = m (delta v)

The Attempt at a Solution

I need some help on question b ASAP (i'm not sure what the question means when it says find the velocity AT THE END of the 1.20 sec impact)
and i would like for someone to check if I've answered question A correctly

 

[Villyer]

A looks right.And for part B, the problem seems set up where that graph of F vs. t is the forces acting on the player for 1.2s. It gives you an initial velocity, and asks what those forces (so the impulse that you already calculated) make her final velocity.

 

[SammyS]

Homework Statement

Homework Equations

fnet(delta t) = m (delta v)

The Attempt at a Solution

I need some help on question b ASAP (i'm not sure what the question means when it says find the velocity AT THE END of the 1.20 sec impact)
and i would like for someone to check if I've answered question A correctly

What does the Impulse - Momentum Theorem say ?

 

[Nitrate]

What does the Impulse - Momentum Theorem say ?

not sure

 

[harts]

The impulse is defined as the integral of a force with respect to time. Wiki "impulse" if you need more help

 

[SammyS]

not sure

Momentum Theorem is something like:

An object's change in momentum is equal to the net impulse on the object.


Look it up to be sure!

 

[Nitrate]

i believe I've found the integral in part A but i don't know what part b means by "find the velocity at 1.20 seconds"

i've got the following information compiled for part b)
fnet(delta t) = m (delta v)
delta t = 1.20 seconds
Fnet = ?
m = 60 kg
vi = 7.0 m/s
vf = ?

my problem is that i don't know what fnet is.

 

[harts]

I=Δp

so you know your initial momentum. Now find the final momentum, using the above fact.

 

[Villyer]

i've got the following information compiled for part b)
fnet(delta t) = m (delta v)

...

my problem is that i don't know what fnet is.

What's the name for fnet(delta t)?

 

[Nitrate]

What's the name for fnet(delta t)?

impulse. however, i don't know if i did part A right and i don't know if they want me to use all the information in question B... and i do not understand what they mean by AFTER 1.20 seconds

 

[SammyS]

... and i do not understand what they mean by AFTER 1.20 seconds

Look at the graph again .

 

[harts]

You have an initial momentum - think about how that impulse ( change in momentum) will change the player's speed. (you're looking for p_f)

 

[Villyer]

impulse. however, i don't know if i did part A right and i don't know if they want me to use all the information in question B... and i do not understand what they mean by AFTER 1.20 seconds

Your part A was right.

And it just means that at t = 0 the velocity is 7, what is the velocity at t = 1.2?

 

[Nitrate]

i think i got it
-360 n*s = 60(vf-7)
-6=vf-7
vf=1 m/s
?

 

[harts]

correct