An astronaut on the Moon releases a rock from rest and allows it to drop straight downward. If the acceleration due to gravity on the Moon is 1.62m/s2 and the rock falls for 2.4s before hitting the ground, what is its speed just before it lands?

speed before landing = 3.9 m/s    (3 s.f.)

Explanation:

As rock is released from rest, u = 0 m/s     a = 1.62 m/s²     t = 2.4 s     v = ?

                      v = u + at

                      v = 0 + (1.62 x 2.4)

                      v = 3.888 = 3.9 s    (3 s.f.)

Hope this helps!

absorption lines are where light has been absorbed by the atom thus you see a dip in the spectrum whereas.

emission spectra have spikes in the spectra due to atoms releasing photons at those wavelengths.

explanation: