According to the second law of Newton, any force reports to a body acceleration if one affects it. Therefore it in proportion depends on it. To calculate force which reports acceleration it is necessary to know the size of this acceleration and body weight.

## It is required to you

- - scales;
- - ruler or roulette;
- - stop watch.

## Instruction

1. By means of scales or any other way determine body weight. Express it in kilograms. After interaction of bodies when to the studied body force is applied, determine the size of the acceleration received by it by the accelerometer. Measure acceleration in m/s². For determination of numerical value of force find the work of body weight of m on its acceleration by a, F = m•a. The direction of force will coincide in this case with the direction of the acceleration received by a body. Receive force in Newtons.

2. Define value of force which reports to a body the acceleration of gravity when the body freely falls. This size is approximately identical in all points of the earth's surface and its average value is equal to m/s g=9.81². For convenience of calculation in many tasks take value 10. Such force is called gravity. Measure the weight of body which freely falls. Calculate gravity, having increased body weight by the acceleration of gravity of Ft = m•g.

3. For example, the body weighing 120 kg on the Earth's surface is affected by Ft gravity = with m·g = of 120•9,81≈1200 N.

4. If the body evenly moves on a circle, acceleration which is called centripetal is reported to it. To find its value, measure the speed of the body moving on a circle. For this purpose by means of a ruler or a roulette measure the radius on which the body, in meters moves. By means of a stop watch measure time of one turn in seconds. It is called the rotation period. Find v=2 speed • π\• R/T where R is the radius of a trajectory, T is the rotation period.

5. Calculate centripetal acceleration. Square value of speed of the movement and divide it into a=v trajectory radius²/R. Calculate force reporting to a body this acceleration. For this purpose increase the body weight measured in advance in any way by acceleration or by the speed square divided into radius: Ft = m • v \.