As preparation for this problem, review Conceptual Example 10. The drawing shows two planes each about to drop an empty fuel tank. At the moment of release each plane has the same speed of 140 m/s, and each tank is at the same height of 4.00 km above the ground. Although the speeds are the same, the velocities are different at the instant of release, because one plane is flying at an angle of 15.0° above the horizontal and the other is flying at an angle of 15.0° below the horizontal. Find the magnitude and direction of the velocity with which the fuel tank hits the ground if it is from each plane. Give the directional angles with respect to the horizontal.

Question

For plane A I got Magnitude -313.045 m/s and direction -64.41, I don't know what I'm doing wrong, I've done the problem several times. Help please!

Answer 1

The magnitudes will be the same. And directions. Think why.

Vf=vI+g*t
the vi is the original velocity, and the gt term is a downward term. The only difference in Vi is the vertical component, but in the upwards angle, gt will be bigger to make the result vf the same.
Magnitue:
Ke at impact=initialKE+mgh
find vf from KE.

Answer 2

I see how the magnitudes and directions will be the same,I just don't understand why I'm getting the numbers wrong.