It is aware of physics besides the usual speed familiar to all from algebra, there is a concept "zero speed". Zero speed or as it is called still, – initial is in a different way, other than a formula of finding of usual speed.
Instruction
1. Zero speed can be found in several ways, each of which is applicable to the tasks containing any given known components.
2. If in a statement of the problem the distance which passed a body (S), time which was required to a body for overcoming distance (t), acceleration with which the body (a) moved then are given it is possible to find zero speed by means of a formula: S=V0t+at^2/2 where V0 is zero speed, t^2 – t in a square. Let S=100 m, t=5 c, a=2 m/c in a square.
3. To find the zero speed (V0) by means of the formula stated above use the rule of the finding of the unknown composed: "To find unknown composed, it is necessary to subtract from the sum known composed". It will turn out: V0t = S-at^2/2.
4. Then apply the rule of finding of an unknown multiplier: "To find an unknown multiplier, it is necessary to divide the work into the known multiplier". It will turn out: V0 = (S-at^2/2)/t.
5. In the received formula substitute values of the known sizes. It will turn out: V0=(100-2x5^2/2)/5, V0= (100-25)/5, V0=15 m/s.
6. When in a statement of the problem instead of distance (S) the final speed (V) to which the body came from the zero speed (V0) is given, for finding of V0 use a formula: V=V0+at, where V – the final speed of a body, and – acceleration with which the body moved, t – time throughout which the body moved. Let V=25 m / c, t=5 c, a=2 m/c in a square.
7. Now for finding of zero speed use the rule of the unknown composed. It will turn out: V0 = V-at. In the received formula substitute the known values. Thus: V0=25-2x5, V0=25-10, V0=15 m/s.