# Thread: projectile shot straight up

1. ## projectile shot straight up

A projectile of mass 1.050 kg is shot straight up with an initial speed of 24.0 m/s.
(a) How high would it go if there were no air friction?
in meters

(b) If the projectile rises to a maximum height of only 23.2 m, determine the magnitude of the average force due to air resistance.
in Newtons

2. Originally Posted by rcmango
A projectile of mass 1.050 kg is shot straight up with an initial speed of 24.0 m/s.
(a) How high would it go if there were no air friction?
in meters
Initial $KE = m v_0^2/2$, $PE =0$

At max height $KE=0$, $PE = m g h_{max}$

So from conservation of energy we have:

$
m v_0^2/2 = m g h_{max}
$

RonL

3. Originally Posted by rcmango
(b) If the projectile rises to a maximum height of only 23.2 m, determine the magnitude of the average force due to air resistance.
in Newtons
Here you know the PE at the maximum height, and the difference between the PE at
max height without air resistence and at this height is the work done against the air
resistance and is equal to the avaerage force times the distance (height) it acted over.

RonL

4. Originally Posted by rcmango
A projectile of mass 1.050 kg is shot straight up with an initial speed of 24.0 m/s.
(a) How high would it go if there were no air friction?
in meters

(b) If the projectile rises to a maximum height of only 23.2 m, determine the magnitude of the average force due to air resistance.
in Newtons
Already answered here. Please don't double post. See rule #1 here.

Frankly I find this kind of behavior insulting. If you didn't understand something about the solution I gave you (or hummeth, too, for that matter) you should have posted a response in the original thread.

-Dan

5. Sorry, no, i double posted by accident, I was in a hurry and i couldn't remember if posted it already.

Again I apoligize, not intentional.

Both the solutions are just fine.