You will need
  • calculator.
The height from which the falling body, the SI units are meters. Acceleration of free fall given in the reference already transferred in units of this system are meters divided by seconds squared. To Land on the middle lane it is 9.81 m/s2. In terms of some of the tasks specified other planets, e.g. the Moon (1.62 m/s2), Mars (3,86 m/s2). When both reference values are given in SI units, the result will be in units of the same system - seconds. And if the condition specified body mass, ignore it. This information is superfluous, it can lead in order to check how well you know physics.
To calculate the time of falling body, multiply the height by two, divide by the acceleration of gravity, and then from the result, extract the square root:

t=√(2h/g) where t is time, s; h - height, m; g - acceleration of free fall, m/s2.
The task may require to find additional information about such things as what was the velocity of the body at the moment of touching the ground or at a certain height from it. In the General case the speed is calculated like this:


Introduced here the new variables: v - velocity, m/s and y is the height of where you want to know the speed of the falling body, m. it is Clear that h=y (i.e., at the initial moment of the fall) speed is zero and when y=0 (at the moment of touching the ground, before the stop of the body) the formula can be simplified:


After the touch of the earth has already occurred and the body is stopped, the speed of his fall again equal to zero (of course, if it is not spryginia and not jumped again).
To reduce the force of impact after free fall parachutes are used. First drop in is free and takes place in accordance with the above equations. Then the parachute opens, and is a smooth deceleration due to air resistance, which now can not be neglected. The patterns described by the above equations no longer apply, and a further reduction in height is slow.