1.

At t = 0, an elevator departs from the ground with uniform speed. At time T1 a child drops a marble through the floor. The marble falls with uniform acceleration g = 9.8 m/s^2, and hits the ground T2 seconds later. Find the height of the elevator at time T1.

Answer»

Let us assume,

The velocity with which the elevatar ascends be u', the height attained by elevatar at time,T1 be h .

Thus,

u' = \(\frac{h}{T_1}\)

Equation of motion,

h = -u'T2\(\frac{1}{2}gT_2^2\)

∵ u' = \(\frac{h}{T_1}\)

h + \(\frac{h}{T_1}\)T2\(\frac{1}{2}gT_2^2\)

h(1 + \(\frac{T_2}{T_1}\)) = \(\frac{1}{2}gT_2^2\) 

h = \(\frac{1}{2}\)\(\frac{gT_2^2}{(1+\frac{T_2}{T_1})}\)



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