## Challlenging problem in Physics

Raptorkiller
Posts: 1
Joined: Fri Oct 07, 2011 10:22 am

### Challlenging problem in Physics

Q) A soldier of parachute regiment has been dropped by a plane flying at an angle 30° with -ve X-axis and at constant speed 200m/s.If the plane was at height of 3km when it dropped the soldier then find the angle of inclination with +ve X-axis a sniper situated at a distance 6km horizontally from the plane at the time of dropping must fire its bullet to hit the soldier.Assume muzzle velocity to be 300m/s.Assume no air resistence. [This an entry level question I will post more tougher ones]
Last edited by Raptorkiller on Sat Oct 08, 2011 1:46 pm, edited 1 time in total.

WhoaNonstop
Posts: 853
Joined: Mon Sep 21, 2009 1:31 am

### Re: Challlenging problem in Physics

This question is way too hard for anyone on this forum to answer. We're only prospective/current graduate students in physics. If this problem contained the Coriolis effect it would be much easier.

-Riley

CarlBrannen
Posts: 381
Joined: Mon May 24, 2010 11:34 pm

### Re: Challlenging problem in Physics

Raptorkiller wrote:Q) A soldier of parachute regiment has been dropped by a plane flying at an angle 30° with -ve X-axis and at constant speed 200m/s.If the plane was at height of 3km when it dropped the soldier then find the angle of inclination with +ve X-axis a sniper situated at a distance 6km horizontally from the plane at the time of dropping must fire its bullet to hit the soldier.Assume muzzle velocity to be 300m/s. [This an entry level question I willl post more tougher ones]

I think it would be rather amazing if the military issued a 6km range sniper rifle with a muzzle velocity of 300 m/s, and then used it to shoot at people moving at 200 m/s, LOL.

Posts: 1
Joined: Tue Oct 18, 2011 7:23 pm

### Re: Challlenging problem in Physics

The bullet and the paratrooper accelerate the same under gravity. Hence, they can be assumed to move with constant velocity without acceleration.

Horizontal closing velocity: 300*cos(theta)+200*cos 30
Vertical closing velocity: 300*sin(theta)-200*sin 30

They will collide if:
6km/Horizontal closing velocity = 3km/Vertical closing velocity

bfollinprm
Posts: 1203
Joined: Sat Nov 07, 2009 11:44 am

### Re: Challlenging problem in Physics

Congratulations, harshadptl, you have reached the first circle of the cult of chall(l)enging problem[s] in physics. But just so everyone knows, that solution fails to consider any pertinent Lorentz boosts, or the macroscopic spin state of the paratrooper. Don't listen to harshadptl, your AP physics teacher will fail you, since it's immediately clear that the haptic energies are non-negligible in a velocitative system.

CarlBrannen
Posts: 381
Joined: Mon May 24, 2010 11:34 pm

### Re: Challlenging problem in Physics

Even ignoring friction it's a fairly tough problem when you include the Coriolis effect.