A free falling body at the moment of impact on the ground reached a speed of 39.2 ms. How high is the UPA body? How long did it fall?

univerkov | December 2, 2020 | education

1) the law of conservation of energy
Ep = Ek
mgh = mv ^ 2/2
2gh = v ^ 2
whence h = v ^ 2 / 2g
h = 39.2 ^ 2 / (2 * 9.8) = 78.4 m.
knowing that the equation of motion has the form S = (Vfinal + Vinitial) * t / 2 we express t
t = 2S / (Vk + Vн)
s = h = 78.4 m
t = 2 * 78.4 / 39.2 = 4 s
Answer:
h = 78.4 m
t = 4 s

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