AI-তৈরি নমুনা উত্তর
Let the height of the tower be h and the total time taken to reach the ground be t seconds.
Since the body falls freely from rest (u=0):
h=21gt2
The distance traveled in the last second (i.e., the t-th second) is:
hlast=21g(2t−1)
According to the question:
hlast=94h
21g(2t−1)=94(21gt2)
2t−1=94t2
4t2−18t+9=0
Solving for t using the quadratic formula:
t=2(4)−(−18)±(−18)2−4(4)(9)=818±324−144=818±180=49±35
Since the fall takes at least 1 second (t>1):
t=49+35≈3.927 s
(The other root t≈0.573 s<1, which is inadmissible).
Taking g=9.8 m/s2:
h=21gt2=21×9.8×(3.927)2≈75.56 m
(Note: If the fraction in the standard textbook problem is 95 instead of 94, then 5t2−18t+9=0⟹(t−3)(5t−3)=0⟹t=3 s, which gives h=21×9.8×32=44.1 m.)