Examkrackers 1001 physics # 156

[moldovanits]

an 8 kg block experiences a net force of 160 n. its velocity increases by 40 m/s. for how long did the force act on the block?
it was 2s but how?>

if f=ma then delta V/T = 2?

I cant figure this one put can someone please help me out?

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[Zen]

It's just a matter of sorting out what you know (force, mass and change in velocity) and connceting them to what you don't know (Time)

Think what equations would lead you to time and are connected to above variables...lets see: force and mass infer f=ma, so perhaps try a=f/m, whereby we can the derive time from the a=v2-v21/time.

So a=f/m= 160/8=20

Now manipulate the acceleration formula to derive time...

Time=v2-v1/a=40/20=2

 

[moldovanits]

It's just a matter of sorting out what you know (force, mass and change in velocity) and connceting them to what you don't know (Time)

Think what equations would lead you to time and are connected to above variables...lets see: force and mass infer f=ma, so perhaps try a=f/m, whereby we can the derive time from the a=v2-v21/time.

So a=f/m= 160/8=20

Now manipulate the acceleration formula to derive time...

Time=v2-v1/a=40/20=2

aha thank you

 

[G1SG2]

an 8 kg block experiences a net force of 160 n. its velocity increases by 40 m/s. for how long did the force act on the block?
it was 2s but how?

Or you can use impulse (just one formula):

F*t=m delta v

160N *t=8 (40)
t=320/160

t=2 seconds