Question

Phyiscs help please

Answer 1

@carmuz will you be able to get this one ..it's the last doubt i cant solve

Answer 2

The target is at the same level at the rifle, so to hit the target, you have to tilt the rifle an angle α.
Now, with that angle, the bullet will travel following a parabolic trajectory:
\[x = \frac{ V^2 sin 2 \alpha }{ g }   \rightarrow   sin 2 \alpha = \frac{xg }{V^2 }\]Where x is the range = 550m.

Then:
sin2α = 0.01358
α = 0.39º

At this point of the problem you will have a right triangle (imagine that), where first catheti is 550m. To know how high above the target you must aim (y = the other catheti), we just have to use:
tan α = y / x -> tan 0.39º = y / 550

Then: y = 3.7 m