# Effect of friction on the foward momentum of an object

1. Mar 3, 2009

### soandos

for example, if a mall is thrown, it forms a parabola, but its speed also decreases due to the friction in air.
what is the formula for that decrease?
what is the shape of the revised curve?
thanks.

2. Mar 4, 2009

### NoobixCube

As a rule of thumb, friction is usually proportional to speed, often quoted as: F(friction)= -bv,
The revised curve is a parabola with a 'squashed' end half.

3. Mar 4, 2009

### Staff: Mentor

I'm guessing you don't mean "shopping mall". That would have a lot of wind resistance, and would not travel very far when you threw it.

A google search on air resistance gives many useful hits. Here's the first{

http://en.wikipedia.org/wiki/Drag_(physics [Broken])

.

Last edited by a moderator: May 4, 2017
4. Mar 4, 2009

### soandos

sorry "mall" was a typo, i meant ball.
another question on this topic:
assuming that a ball is thrown at a 100mph (in regular air) does that have a high Reynold's Number or not?
sorry, i do not take physics, so this might be a stupid question.