The body freely falls from a certain height at the moment of falling, its speed is 30 m / s. from what height did the body fall?
v = 30 meters per second – the speed of the body at the moment of falling to the ground from a certain height;
g = 10 meters per second squared – gravitational acceleration (constant near the Earth’s surface).
It is required to determine h (meter) – the height from which the body fell.
Since, according to the condition of the problem, the body fell freely, that is, without an initial velocity, then, according to the law of conservation of energy, its potential energy at height h is equal to the kinetic energy at the moment of falling:
Epot = Ekin;
m * g * h = m * v ^ 2/2, where m is body weight;
g * h = v ^ 2/2;
h = v ^ 2 / (2 * g) = 30 ^ 2 / (2 * 10) = 900/20 = 90/2 = 45 meters.
Answer: the body fell from a height of 45 meters.
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