"The invention of the bicycle" is actually not as bad as can seem at first sight. When studying a course of physics to school students often suggest to calculate the known value long ago: acceleration of gravity. Once calculated independently, it settles in the heads of pupils much more densely.
Instruction
1. The law of universal gravitation is that all bodies in the Universe are attracted the friend to the friend with a bigger or smaller force. It is possible to find this force from the equation: F=G*m1*m2/r^2 where G is the gravitational constant equal 6.6725 * 10^(-11); m1 and m2 – the mass of bodies, and r – distance between them. This law, however, describes the total force of an attraction of both ph. now it is necessary to express F for each of two objects.
2. According to Newton's law F=m*a, i.e. performing acceleration on weight also gives strength. Proceeding from it, the law of universal gravitation can be written down as m*a=G*m1*m2/r^2. At this m and and, standing in the left part, can be as parameters of one body, and the second.
3. It is necessary to construct the system of the equations for two bodies where in the left part there will be m1*a1 or m2*a2. If to reduce m standing in both members of equation, then laws of change of acceleration a1 and a2 will turn out. In the first case of a1=G*m2/r^2 (1), in the second a2=G*m1/r^2 (2). Total acceleration of an attraction of objects is a1+a2 sum.
4. Now it is worth making assessment of the equations taking into account an objective – findings of forces of universal gravitation between the earth and a body, close to it. For simplicity the assumption that the attraction comes at the expense of Earth kernel (i.e. the center), and therefore r = to distance from a kernel to an object, i.e. to planet radius becomes (rise over a surface is considered negligible).
5. The second equation can be rejected: in numerator there is a m1 value first about (kg) while the denominator has-11+(-6), i.e.-17 order. It is obvious that the turned-out acceleration is negligible.
6. Acceleration of a body on the Earth's surface can be defined by substitution instead of m2 of mass of the earth, and instead of r – radius. a1=6.6725*10^ (-11) *5.9736*10^24 / (6.371*10^6) ^2=9.822.