9. Un automóvil parte del reposo y se acelera uniformemente a 10 m/s2 para pasar dos semáforos consecutivos que se encuentran separados 200 m. Si el vehículo tarda 4s en pasar los dos semáforos, determine la distancia a la que se encuentra el primer semáforo del punto de partida.

Given:

M=10KG

F=42N

Opposing Force=6N

If we can recall F=ma, we can easily calculate the acceleration by substituting the given variables; but in our case, we have an opposing force. So we have to subtract the opposing force from the horizontal force.

F = ma

42N-8N=10KG x a

34N = 5KG x a; divide both sides by 10KG for a to be sole variable

34kg m/s^2) / 10kg x a (Newtons are sometimes referred to as kg m/s^2)

3.4 m/s^2 = a ; (kg's are cancelled)

Therefor, our acceleration is 3.4 m/s^2.