Question

Near the surface of the Earth a ball is tossed straight up. If the ball returns to its starting point 3 seconds later, what maximum height did the ball reach (in m)? Ignore air resistance

Answer 1

What equations do we have for this system?

Answer 2

change in velocity in the y= acceleration x change in the time
change in the y= .5 (v(final)-v(initial)x change in time
change in y= v(initial)x change in time +.5 x acceleration x change in time^2
velocity(final)^2-v(initial)^2=2acceleration x change in y


right?

Answer 3

let's try a different approach, what is the velocity at the top of the arc?

Answer 4

velocity would be 0

Answer 5

right, so I am not sure if these are your eq (my brain doesn't like to understand today) but these are the three you can choose from pick one that uses the least information \[v_f=v_i+at\]\[v_f^2=v_i^2+2ax\]\[x=v_it+\frac{1}{2}at^2\]

Answer 6

let's call them, 1,2,3 which one requires no other information?

Answer 7

3

Answer 8

right what is our \(v_i\)?

Answer 9

0

Answer 10

but i dont see how it could be zero because its thrown upwards?

Answer 11

It's the same distance from the top to the bottom right?
The acceleration is the same throughout the system too right?

Answer 12

what is our a?

Answer 13

yeah it is and the a=mg

Answer 14

not quite

Answer 15

so would it just be -9.8 m/s^2

Answer 16

yup, just g

Answer 17

okay so x= -44.1?

Answer 18

walk me through how you got that

Answer 19

using the 3rd equation \[x= 0 +\frac{ 1 }{ 2 }(-9.8)(3)^2\]

Answer 20

Good,

Answer 21

I would say positive though because it is going up, and use 2 decimal points

Answer 22

according to the answer key it says its 11... I'm not sure how they got that or is it just a typo? (its from a previous exam)

Answer 23

ok, let me take another look at it after class ok?

Answer 24

sure thanks!!

Answer 25

yup wrong time, t a

Answer 26

it takes 3 seconds from bottom to top and back, so how long to just get to the top?

Answer 27

1.5s

Answer 28

try that for t

Answer 29

it right!!! you're the best! its been killing me so I really appreciate it!

Answer 30

Alright, good job with the leg work!

Answer 31

gtg class!

Answer 32

good luck