# Homework Help: How do I determine the maximum distance, that the ball moves upward, and the time for

1. Jun 30, 2012

### R Morrison

1. The problem statement, all variables and given/known data

I want to learn how to solve problems with air resistance.
The equation is shown at the website below.
http://en.wikipedia.org/wiki/Drag_(physics [Broken])

Example:
A 0.5 kg ball is thrown upward at 25 m/s. The density of the air = 1.3 kg/m^3. The drag coefficient = 0.8. Cross sectional area = 0.05 m^2

Fd = ½ * 1.3 * v^2 * 0.8 * 0.05
Fd = 0.026 * v^2
How do I determine the maximum distance, that the ball moves upward, and the time for the upward trip?

2. Relevant equations

Fd = ½ * density * velocity^2 * drag coefficient * Cross sectional area

3. The attempt at a solution

Fd = ½ * density * velocity^2 * drag coefficient * Cross sectional area
Fd = ½ * 1.3 * v^2 * 0.8 * 0.05
Fd = 0.026 * v^2

Net force = m * g – Force of air resistance
Net force = (0.5 * 9.8) – 0.026 * v^2
Net acceleration = Net force ÷ mass
Net acceleration = 9.8 – 0.052 * v^2

How do I determine the maximum distance, that the ball moves upward, and the time for the upward trip
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

Last edited by a moderator: May 6, 2017
2. Jun 30, 2012

### R Morrison

Re: How do I determine the maximum distance, that the ball moves upward, and the time

What does edit tags meam?

3. Jun 30, 2012

### sckeen1988

Re: How do I determine the maximum distance, that the ball moves upward, and the time

First, mg is acting against the initial motion of the ball, so it should be negative. From that it may be a good place to start to solve for the initial net acceleration of the ball. Then remember that a=dv/dt