Physics

The dimension of Planck constant equals to that of angular momentum.

Both stones reach the ground at the same time. The initial speed is 0 for both stones, and the only acceleration working in that system would be g (Gravity acceleration). So, as the distance is the same, the final speed will be the same time. The only reason which could change this result is a difference in the shape of the stones. While they fall to the ground, they must “open” a way across the air. The shape of the falling object will decide the force needed to open that way. This is called the “Air resistance”. Depending on the shape of the object, the resistance force will be bigger or smaller. As this force works counter to g, the falling time will decrease. Between a feather and a plumb ball, the falling time will be the same in vacuum, but inside air, the resistance force for the feather has almost the same value than gravity, while for the ball, the resistance is very much weaker than gravity.

The ozone layer is a layer in Earth’s atmosphere containing relatively high concentrations of ozone (O3) which absorbs 97–99% of the Sun’s medium-frequency ultraviolet light.

Light travels faster in vacuum as compared to any other medium. This is because there is no obstruction in the propagation of light in vacuum as there is no matter in vacuum and also, because the refractive index of vacuum is the lowest i.e. equal to unity.