Question

A boy drops a ball from an observation tower. The ball hits the ground in 5.0 s. What is the ball's velocity at the time of impact?
A. 0 m/s
B. 98 m/s
C. 49 m/s
D. 123 m/s

**not quite sure how to solve this :( thanks!!!

Answer 1

In case of dropping the initial velocity is always 0m/s
acceleration due to gravity is g = 9.8m/s^2
Use the equation \(\sf v=u+gt\) to find the value of v

Answer 2

u=initial velocity

Answer 3

okie:) so is initial velocity 0? :/

Answer 4

yes

Answer 5

Another rendition of that formula is \[v_f = v_i + a_gt\]

Answer 6

so v=u+gt
v=0+(9.8)(5) ?

Answer 7

v=49 m/s ?

Answer 8

\(\huge \checkmark\)

Answer 9

There are three equations of motion

Answer 10

yay!! thanks so much :)

Answer 11

\(\bullet\) v=u+at
\(\bullet\) \(\sf s=ut+\frac{1}{2}at^2\)
\(\bullet\) \(\sf v^2=u^2+2as\)

Answer 12

okie :) i will try to remember them all haha

when do i know when to apply a specific equation?

Answer 13

v=final velocity
u=initial velocity
t=time
a=acceleration

Answer 14

s=distance

Answer 15

okie:)

Answer 16

thanks!! so i just figure out which one to use based on the info they give me?

Answer 17

Yes

Answer 18

okie yay!! thanks!! :D

Answer 19

In projectile motion there are two components of initial velocity....
The vertical component is 0 but the horizontal component is not zero

Answer 20

Ahh okay! I shall try to keep that in mind!!:)