zad.1.
72 km/h = 72000 m/3600 s = 20 m/s
1 km = 1000 m
1 h = 3600 s
zad.2.
R = 6470 km = 6470000 m = 6,47 *10^6 m
g = 9,81 m/s^2
G = 6,67 *10 ^-11 N *m^2/kg^2
Mz = ?
m*g = G *Mz *m /R^2 ; dzielę obustronnie przez m
g = G *Mz /R^2
g * R^2 = G * Mz
*Mz = g R^2/G
Mz = 9,81 m/s^2 * (6,47 *10^6 m)^2 / 6,67 *10^-11 N *m^2/kg^2
Mz = 9,81 m/s^2 * 40,6 *10^12 m^2 /6,67 *10^-11
Mz = 398,3 *10 ^12 m^3/s^2 / 6,67 *10^-11 N *m^2/kg^2
Mz = 59,7 *10^23 kg
Mz = w przybliżeniu 6 *10^24 kg
zad.3.
F = 40 kN = 40000 N = 4 *10^4 N
t = 45 s
V = 108 km /h = 108000 m/3600 s = 30 m/s
m = ?
F = m * a
a = V/t
F = m V/t
Ft = m *V
m = F * t /V
m = 4 10^4 N * 45 s /30 m/s
m = 180 ^10^4 kgm/s^2 * s /30 m/s
m = 6*10^4 kg