Height of the 15 storeyed building would be 15x3 = 45 m. Hence distance traveled by the text book will be 45 metres.

For motion under gravity, the distance traveled S is given by the 2^nd equation of motion S= ut+ ½ gt^2, where u is the initial velocity, which in this case is =0

Hence S= ½ gt^2 . Substituting the values for S and g, we will have

45= ½ (9..8) t^2,

t^2= 45/4.9

t= 3.03 seconds

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