how long after the big bang was the planck time, the time at which our current theories become completely unable to describe conditions any earlier in the universe?

explanation:

as the height from which the ruler was dropped increased, the speed of the ruler at ryan's hand increased.

initial speed when it is dropped is 150 ft/s

now at the same moment the acceleration due to gravity is perpendicular to its velocity

so as we know that

now we have centripetal acceleration a = 32 ft/s^2 as its perpendicular to velocity

while tangential acceleration at the same moment will be zero

so

now radius of curvature is given as

so the radius of curvature just after it is dropped is 703.125 ft