Can someone help me? I'm a substitute for a high school physics class and...

[immrspotatoehead]

...I think my answer key is wrong!? Thanks!

An airplane has a speed of 260 km/h with respect to the air. There is a wind blowing at 95 km/h at 30° north of east with respect to Earth. In which direction should the plane head in order to land at an airport due north of its present location?
What would be the plane's speed with respect to the ground?

A stone is thrown horizontally at a speed of 4.2 m/s from the top of a cliff 81.8 m high.
(a) How long does it take the stone to reach the bottom of the cliff?
(b) How far from the base of the cliff does the stone hit the ground?
(c) What are the horizontal and vertical components of the stone's velocity just before it hits the ground?

If a small planet, D, were located 9.5 times as far from the Sun as Earth is, how many years would it take the planet to orbit the Sun?

Two spheres are placed so that their centers are 2.7 m apart. The force between the two spheres is 2.55 10-12 N. What is the mass of each sphere if one sphere is twice the mass of the other sphere?