Question

A ball accelerates uniformly at +4.0 m/s^2. If the ball was initially moving at +0.20 m/s and the average velocity was +4.2 m/s, then how long will it take it to reach the final velocity?

2.0 s, 2.2 s, 8.2 s, or 10.0 s

? :/ @jim_thompson5910 :)

Answer 1

list out what you have

Answer 2

I'll start you off

a = 4

Answer 3

okie:)

so a=4.0
vi=0.20
(not sure what 4.2 is though!)

Answer 4

would it be vf? :/

Answer 5

so of vf isnt there, do i use the same equation as last one?

d=vi(t)+1/2at^2 ?

Answer 6

one sec

Answer 7

kk:)

Answer 8

well if the ball is moving along a straight path, then the average velocity w is

w = (vi + vf)/2

that sounds right I think

Answer 9

okie:)

so 4.2=(0.20+vf)/2
4.2=0.10+1/2vf
4.1=1/2vf
8.2 = vf ?

Answer 10

ok that looks correct, vf = 8.2

Answer 11

ahhh yay!! thank you, makes so much sense now!! just need to remember the formulas though haha :P okay, let me post the last(!!) one!! :)

Answer 12

well 8.2 wasn't the answer

Answer 13

that was just vf

Answer 14

you need to find s

Answer 15

ahhh oops!! misread lol :P looked over the "how long" part :P lol

okay, so finding s (aka t for time right?)

using vf=vi+at ? since we are not given a distance?

Answer 16

8.2=0.20+4t
8=4t
t=2 ?

so it will take 2.0 s to reach the final velocity?

Answer 17

a=4.0
vi=0.2
vf = 8.2

not given d
not given t

we want to solve for t and we don't care about d, so yes we use vf = vi + a*t

Answer 18

yay! so we get 2.0? :D

Answer 19

yes t = 2

Answer 20

yay!! okay now onto the last one lol:P

thanks!! :D