CBSE Class 11-science Answered

Take upward direction as positive and downward direction as negative.

Let height of tower be h and time of fall be t.

Either use formula for distance travelled in the nth second or find velocity at the end of t-1 seconds and use this as initial velocity for last one second of its fall.

As the body falls through 60.1m so it will have a negative sign, acceleration is also in the downward direction so it is negative.

S_n = u +1/2a(2n-1)

-60.1 = 0 +1/2(-9.8)(2n-1)

Solve for n.