Question

Sandra throws an object into the air with an initial vertical velocity of 38 feet per second, from a platform that is 30 feet above the ground. How long will it take the object to hit the ground?

Answer 1

@hartnn

Answer 2

use the equations of motion for constant acceleration

here we have a displacement (s) of -30 ft , initial velocity (u) of 38 ft/s and the acceleration (a) is that due to gravity which is -32 ft/s^2 and you need to find time.

use s = ut + 0.5at^2 and solve for t

Answer 3

alright ill give it a shot

Answer 4

0.5at^2 + tu = -30

Answer 5

nope im wronge ill try again

Answer 6

Okay i'm missing something here. Could you show what you would do?

Answer 7

s = -30, u = 38 and a = -32

so we get
-30 = 38t - 0.5*32*t^2
-30 = 38t - 16t^2

now solve this quadratic equation ffor t
you'll have 2 solutions on positive and other negatrive
the positive one will be the rquired time

Answer 8

Okay, That clears it up Thank you for your help!

Answer 9

yw

Answer 10

It's 3!!

Answer 11

yes

Answer 12

WhooHooo!

Answer 13

you just got your self another fan!

Answer 14

there are 4 of these equations

v = u + at
s = ut + 0.5at^2
v^2 = u^2 + 2as
ans s =2 (U +v) / t

v = final velocity

they are very useful for solving problems of motion under gravity