Question

If the spheres are 19.6 meters above the ground, the time required for the aluminum sphere to reach the ground is
(1) 1s
(2) 2s
(3) 8s
(4) 4s

Answer 1

2. Two seconds

Both spheres will reach the ground at the same time. 

use the formula t=sqrt(2h/g) = sqrt(2(19.6)/9.8) = 2 seconds

mass does not contribute to fall time, despite having greater potential energy. 

Answer 2

Answer:

(2) 2s

Explanation:

Remember that the time that it takes an object to fall from a certain distance is only determined by the force with which the object is pulled towards the center of the earth which is gravity, so any object with 0 velocity will drop at the same rate to the ground when dismissing resistance from the air, in to calculate this you just have to use the next formula:

$H=\frac{g*t^2}{2}\\ t=\sqrt{\frac{2H}{g} }$

So we just insert the data that we have into the formula:

$t=\sqrt{\frac{2H}{g} }\\t=\sqrt{\frac{2*19,6}{9,81} }\\t=\sqrt{4}\\ t=2 seconds$