Question

In a game war, one team sets base on a cliff 15m high and 60m away from the
opponent’s base. At what velocity must the attack be launched so that the lower base
will be hit? The initial launch is at 20 degrees below the horizontal?

Answer 1

Given:

In a game war

height of the cliff $h=15\ m$

length away from the opponents base $x=60\ m$

To Find:

Velocity at which the attack be launched

Solution:

The velocity can be calculated by the use of the equation below

$0=h-vsin20t-0.5gt^{2}$

$0=15-vsin20t-0.5(9.8)t^{2}$

$x=vcos20t$

$T=\dfrac{60}{vcos20\textdegree}$

$0=15-\dfrac{60}{cos20\textdegree}\times sin20\ -0.5(9.8)\dfrac{60^{2} }{v^{2}cos^{2} 20 }$

$v=54\ m/s$

The velocity that the attack is launched is $54$ m/s.