Question

A car waits at a ref light for a few seconds, and then accelerates straight ahead to 54km/h in 3.1s and then cruises at a constant speed for 75m. Find the total distance and time travelled

Answer 1

1a)
x1=vt
x1=25*0.85=21.25 m

1b)
a=v/t
a=25/3.5=2.2 m/s^2
x=v^2/(2a)+x1
x=625/4.4+21.25=163.3 m

c)
a=v/t
a=25/3.5=2.2 m/s^2

2)
a=v/t=15/3.1=4.8 m/s^2
x1=v^2/(2a)
x1=225/9.6=23.4 m (while accelerating)
x2=vt=15*4500=67,500 m
total distance is
x=x1+x2=23.4+67,500=67,523.4 m =67.523 km