Because other scientists and science in general rely on their collegues' research which in turn allows development of our knowledge on the given subject. The more dont-to-earth reason may be safety. If someone performs an experiment without knowledge of its true results it might result in some danger to the safety of those perforning it without knowledge of all the risks.
Answer:
1.98 m/s
Explanation:
To solve this, we would be using the law of conservation of energy, i.e total initial energy is equal to total final energy.
E(i) = E(f)
mgh = ½Iw² + ½mv²
Recall, v = wr, thus, w = v/r
Also, I = ½mr²
I = 0.5 * 5 * 2²
I = 10 kgm²
Remember,
mgh = ½Iw² + ½mv²
Substituting w for v/r, we have
mgh = ½I(v/r)² + ½mv²
Now, putting the values in the equation, we have
5 * 9.8 * 0.3 = ½ * 10 * (v/2)² + ½ * 5 * v²
14.7 = 1.25 v² + 2.5 v²
14.7 = 3.75 v²
v² = 14.7/3.75
v² = 3.92
v = √3.92
v = 1.98 m/s
Thus, the speed is 1.98 m/s
They had to use thrust because there is no air on the moon meaning that parachutes would be totally useless because parachutes require air to create drag. Fun fact since there is no air on the lunar surface sound waves cannot be made since there are no air molecules for the waves to pass through, so that's why they use radio's in space.