Register to reply

Object thrown vertically

by kimikims
Tags: object, thrown, vertically
Share this thread:
kimikims
#1
Sep24-04, 02:07 PM
P: 36
An object is thrown vertically upward such that it has a speed of 58 m/s when it reaches two thirds of it's maximum height above the launch point.
The acceleration of gravity is 9.8 m/s^2

Find the maximum height h. Answer in units of m.


I know:

V: 58 m/s at y=2/3 H
H = ?
V = 0

V^2-Vo^2 = 2g(1/3H)

I know I need to plug in the numbers, but how do I get all of the equation to one side, to find H??
Phys.Org News Partner Science news on Phys.org
Security CTO to detail Android Fake ID flaw at Black Hat
Huge waves measured for first time in Arctic Ocean
Mysterious molecules in space
Doc Al
#2
Sep24-04, 02:24 PM
Mentor
Doc Al's Avatar
P: 41,325
Quote Quote by kimikims
V^2-Vo^2 = 2g(1/3H)
Right (where Vo = 0).

I know I need to plug in the numbers, but how do I get all of the equation to one side, to find H??
Divide or multiply both sides to eliminate what's in front of H.

For example, if you had an equation: 7x^2 = 67bZ, and you wanted to isolate Z, just divide both sides by 67b: (7x^2)/67b = (67bZ)/67b = Z; so Z = (7x^2)/67b. Make sense?
Pyrrhus
#3
Sep24-04, 02:26 PM
HW Helper
Pyrrhus's Avatar
P: 2,278
You got

[tex] V^2 = V_{o}^2 + 2g\frac{2}{3}H [/tex]

where V is 58 m/s

and

[tex] 0 = V_{o}^2 + 2gH [/tex]

Pyrrhus
#4
Sep24-04, 02:28 PM
HW Helper
Pyrrhus's Avatar
P: 2,278
Object thrown vertically

Doc Al, how come initial speed = 0 ?
Doc Al
#5
Sep24-04, 02:35 PM
Mentor
Doc Al's Avatar
P: 41,325
Quote Quote by Cyclovenom
Doc Al, how come initial speed = 0 ?
If you look at the motion on the way down, then the object starts from rest and falls a distance of H/3 to reach a speed of 58 m/s.
Pyrrhus
#6
Sep24-04, 02:36 PM
HW Helper
Pyrrhus's Avatar
P: 2,278
Quote Quote by Doc Al
If you look at the motion on the way down, then the object starts from rest and falls a distance of H/3 to reach a speed of 58 m/s.
Oh Yes, i wasn't thinking about it


Register to reply

Related Discussions
Pulling a box vertically Introductory Physics Homework 2
Particle projected vertically Introductory Physics Homework 4
Net velocity of thrown object-lost Introductory Physics Homework 10
Thrown Object General Physics 6
Speed of an object thrown down a hole to the center of the earth Introductory Physics Homework 1