- #1

- 85

- 3

## Homework Statement

An airplane flies horizontally with a speed of 300m/s at an altitude of 300m. Assume the ground is level. At what horizontal distance from a target must the pilot release a bomb as to hit the target?

Answer: 2.7km

## Homework Equations

a=v/t=d/t

^{2}

r_f = r_i + v_i*t + 1/2at

^{2}

## The Attempt at a Solution

I tried approaching this question using a kinematics equation and just the basic a=v/t approach...

a=v/t=d/t

^{2}

t = sqrt( 2 * d / g ) = 9s

d(horizontal) = vt = (300)(9) = 2.7km

r_f = r_i + v_i*t + 1/2at

^{2}

Using the quadratic equation to find t = 62.5s

d(horizontal) = (300)(62.5) = 18.7km

*Why*can I not use the kinematics equation to approach this problem?

In general, how do I know whether its appropriate to approach a problem using kinematics vs. the "basic" equations (a=v/t; v=d/t)?