a) Eine Sprinterin ...
v = a * t
12 m/s = a * 4 sec
a = 3 m/s^2
s = v / 2 * t
s = 12 / 2 * 4 = 24 m
oder
s = 1/2 * a * t^2
s = 1/ 2 * 3 * 4^2 = 24 m
b) Eine Radfahrerin ...
28 km/h = 7.777 m/s
10 = 2.777 m/s
2.777 = 7.777 - a * 1
a = - 5 m/s^2
F = m * a = ( 45 + 25 ) kg * 5 m/s^2
F = 350 kg * m/s^2 = 350 N