Answer:
7.4 km/h
Step-by-step explanation:
Since this involves momentum conservation, apply the principle of linear momentum.
The principle of linear momentum states that:
[tex]m_{1}u_{1}[/tex] + [tex]m_{2} u_{2}[/tex] = ([tex]m_{1}[/tex] + [tex]m_{2}[/tex])V
where: [tex]m_{1}[/tex] is the mass of the man, [tex]u_{1}[/tex] is the velocity of the man, [tex]m_{2}[/tex] is the mass of the car, [tex]u_{2}[/tex] is the velocity of the car, and V is the common velocity of the man and car.
But, since the car was initially at rest, [tex]u_{2}[/tex] = 0.
70 x 18 + 100 x 0 = (70 + 100)V
1260 = 170V
V = [tex]\frac{1260}{170}[/tex]
= 7.4118
V = 7.4 km/h
The car and man would start to move with a velocity of 7.4 km/h.
