# Math Help - projectile motion

1. ## projectile motion

A bomb is released from a plane which is diving at an angle of 30 degrees from the vertical . The plane is at a height of 1000m when the bomb is released . The bomb hits the ground 10s later . What is the speed of the plane when the bomb is released .

My attempt :

$s=ut+\frac{1}{2}at^2$

$1000=usin30(10)+frac{1}{2}(9.81)(10)^2$

$
u= 101.9 mms^{-1}
$

But it is wrong .. Wonder where my mistake is .. THanks for helping me out .

A bomb is released from a plane which is diving at an angle of 30 degrees from the vertical . The plane is at a height of 1000m when the bomb is released . The bomb hits the ground 10s later . What is the speed of the plane when the bomb is released .

My attempt :

$s=ut+\frac{1}{2}at^2$

$1000=usin30(10)+frac{1}{2}(9.81)(10)^2$

$
u= 101.9 mms^{-1}
$

But it is wrong .. Wonder where my mistake is .. THanks for helping me out .
Diving 30 degrees from the vertical = diving 60 degrees from the horizontal.

Initial downward velocity component is v sin(60) m/s not v sin(30) m/s, where v is the plane's speed at weapon release.

CB