Determine the acceleration of the rocket during vertical launch if the astronauts are experiencing a fourfold overload.

P = 4 * m * g.
g = 9.8 m / s ^ 2.
but – ?
When the rocket takes off, 2 forces act on the cosmonauts: the force of gravity m * g, directed vertically downward, and the reaction of the rocket floor (the force with which the floor presses on the astronauts’ feet) N, directed vertically upward.
Let’s write 2 Newton’s law on the axis directed vertically upwards: m * a = N – m * g.
Let us express the strength of the sex reaction: N = m * a + m * g.
According to Newton’s 3 law, the weight of a body is equal to the force with which the floor presses on the legs: N = P.
P = m * a + m * g.
a = (P – m * g) / m.
a = (4 * m * g – m * g) / m = 3 * g.
a = 3 * 9.8 m / s ^ 2 = 29.4 m / s ^ 2.
Answer: the acceleration of the rocket is directed vertically upwards and is a = 29.4 m / s ^ 2