A rock is dropped from the top of a tall building The rocks

A rock is dropped from the top of a tall building. The rock\'s displacement in the last second before it hits the ground is 43% of the entire distance it falls. How tall is the building? Express your answer with the appropriate units. h= _____ ____

Solution

here,

let the height of building be h

the distance travelled by rock before last seccond , d\' = (1 - 0.43) * h = 0.57 * h

the speed of rock before the last seccond , u\' = sqrt(2*d\'*g)

u\' = sqrt(2*0.53 * h * 9.81) ....(1)

for the last seccond

0.47 * h = u\'* t + 0.5 * g * t^2

0.47 * h = sqrt(2*0.53 * h * 9.81) * 1 + 0.5 * 9.81 * 1^2

solving for h

h = 66.3 m