Final answer:
To determine the time it takes for the body to reach the ground, we need to find the total time of its journey. The correct answer is option (C) 5 sec.
Step-by-step explanation:
To determine the time it takes for the body to reach the ground, we need to find the total time of its journey. Let's assume that the body takes t seconds to reach the ground from the top of the tower. In the last second of its journey, it covers a distance of 7x, where x is the distance covered in the first second. Therefore, in the last second, the body covers a distance of 7(1)x = 7x. We can write the equation:
75 = 7x + (t-1)x + x
75 = 9x + tx
75 = x(9 + t)
Let's analyze the options given:
If we substitute t = 3, we get x = 7.5. But, 9 + t = 12 ≠ 0, so this option is not valid.
If we substitute t = 4, we get x = 5. But, 9 + t = 13 ≠ 0, so this option is not valid.
If we substitute t = 5, we get x = 3.75. In this case, 9 + t = 14 = 0, so this option is valid. Hence, the time it takes to reach the ground is 5 seconds.
Therefore, the correct answer is option (C) 5 sec.