For finding of change of speed decide on type of the movement of a body. In case the movement of a body evenly, change of speed is equal to zero. If the body moves with acceleration, then change of its speed in each timepoint can be learned if to take away from instantaneous velocity at present of time its initial speed.

## It is required to you

- stop watch, speedometer, radar, roulette, accelerometer.

## Instruction

1. Definition of change of speed is any the help of the speedometer or the radar moving on a straight line trayektoriis measure body speed in the beginning and the end of a piece of a way. Then from the end result take away initial, it also will be change of speed of a body.

2. Definition of change of speed of the body moving with an uskoreniyemnaydita acceleration of a body. Use the accelerometer or a dynamometer. If body weight, then force operating on a body is known, divide into its weight (a=F/m). After that measure time for which there was a process of change of speed. To find change of speed, increase value of acceleration for a while for which there was this change (Δv=a•t). If to measure acceleration in meters per second squared, and time - in seconds, then speed will turn out in meters for a second. If there is no opportunity to measure time, but it is known that speed changed on a certain piece of a way, a speedometer or the radar, measure speed at the beginning of this piece, then by means of a roulette or a range finder measure length of this way and acceleration. Measure by any of the above methods acceleration which affected a body. After that find the final speed of a body at the end of the site of a way. For this purpose square initial speed, add to it the work of length of the site on acceleration and number 2. Take a square root from result. To find change of speed, from the received result take away value of initial speed.

3. Definition of change of speed of a body at povoroteesl not only the size, but also the direction of speed changed, find its change through the vector difference of initial and final speed. For this purpose measure a corner between vectors. Then from the sum of squares of speeds take away the doubled their work increased by a cosine of the angle between them: v1²+v2²-2v1v2•Cos(α). Take a square root from the received number.