Physics problem

1. Sep 15, 2004

lmf22

physics problem....

A hunter aims directly at a target (on the same level) 100m away.
a) If the bullet leaves the gun at a speed of 250m/s, by how much will it miss the target?
b) At what angle should the gun be aimed so the target will be hit?

Any help would be great. Thanks.

2. Sep 15, 2004

arildno

What have you done so far?

3. Sep 15, 2004

lmf22

I set up the axis where the hunter is Y meters up and the target is also Y meters up to 100m to the right.
The X component of the velocity is 250m/s and Y component is 0.

For part a)
I used the distance formular in the Y and X components so:
Y = Yi + vi*t + 1/2*a*t^2.
X = Xi + vi*t + 1/2*a*t^2.

Y=0
Vi=0
Xi=0
a in the X component = 0

From the X component of the distance formular I solved for time =0.4s.
Then I plug in the time into the Y component of the distance formula and got 39.2m.

I'm not sure where to start for part b).

4. Sep 15, 2004

arildno

Note that given initial speed V0, and angle a to the horizontal, we may write:
Initial horizontal velocity: V0cos(a)
Initial vertical velocity: V0sin(a)

Find the time T from the horizontal component (that is, which yields final horizontal position equal to 100)
Determine a by requiring that at this time T, final vertical position must be zero (equal to initial level)