Final answer:
The vertical velocity of a freely falling body at the 5th second, assuming standard gravity, is 49 m/s. This is calculated using the formula v = u + at with an initial velocity (u) of 0 m/s and gravity (a) at 9.8 m/s^2.
Step-by-step explanation:
To determine the vertical velocity of a freely falling body at the 5th second, we can use the equation of motion under the influence of gravity, where v = u + at. In this problem, since the body is freely falling, the initial velocity (u) is 0 m/s. Assuming standard gravity, which is 9.8 m/s2, the velocity (v) at the 5th second would be given by:
v = 0 + (9.8 m/s2)(5 s) = 49 m/s.
Here, 'a' is the acceleration due to gravity and 't' is the time in seconds. Therefore, the correct answer is option (b) 49 m/s.