Question

A fighter-bomber is making a bombing run flying horizontally at 500 knots (100 m/s). At an altitude of 100 m. a. How long will it take for the bomb to hit the ground after it is dropped from the plane

Answer 1

Answer:

$5\:\mathrm {s}$

Explanation:

We can use kinematics equation $\Delta y={v_i}t+\frac{1}{2}at^2$ to solve this problem. Since $v_i$ in the vertical direction is $0$, we have:

$\Delta y =\frac{1}{2}at^2$ (freefall equation)

Plugging in values, we get:

$100=\frac{1}{2}\cdot 9.81\cdot t^2,\\\\t^2=\frac{100}{\frac{1}{2}\cdot 9.81},\\\\t=\sqrt{20.387}\\\\t=4.515\approx \fbox{ 5\:\mathrm{seconds} }$(one significant figure).

*The horizontal velocity is irrelevant in this question. It only affects the horizontal displacement of the object (where the object lands), not how long it takes for the object to hit the ground.