With what force does the load press on the bottom of the lift, on which the force of gravity 980N acts, if the lift moves with acceleration of 0.245m / s2 directed upward? Directed downward? Does the pressure force depend on the direction of movement? free falling elevator?
Ft = 980 N.
g = 9.8 m / s2.
a = 0.245 m / s2.
The force with which the load presses on the floor is called the body weight R.
Two forces act on the load: gravity Ft directed vertically downward, force N, with which the floor presses on the load, directed vertically upward.
m * a = F + N – 2 Newton’s law in vector form.
For projections onto the vertical axis 2, Newton’s law will take the form: m * a = – Ft + N.
N = m * a + Fт.
The force of gravity Ft is determined by the formula: Ft = m * g.
m = Fт / g.
N = a * Ft / g + Ft.
According to Newton’s 3 laws, the force N with which the floor presses on the load is equal to the force P with which the load presses on the floor P: N = P.
P = a * Ft / g + Ft.
P = 0.245 m / s2 * 980 N / 9.8 m / s2 + 980 N = 1004.5 N.
With the direction of acceleration a downward: – m * a = – Ft + N.
N = Ft – m * a = Ft – a * Ft / g.
P = Ft – a * Ft / g.
P = 980 N – 0.245 m / s2 * 980 N / 9.8 m / s2 = 955.5 N.
In a freely falling elevator, the load will be from zero gravity, therefore P = 0 N.
Answer: with acceleration directed upwards P = 1004.5 N, acceleration directed downward P = 955.5 N.