Question

The driver of an ambulance sees a bus 40 m ahead of him after 20 seconds the bus is 60 meter behind .if the speed of the ambulance is 30km/h what is the speed of the bus

Answer 1

Let the velocity of ambulance be x and velocity of the bus be y.
Also suppose that, the velocity of the ambulance with respect to the bus be z. Then,
z = x + y   ..... (1)
Given that, the driver of an ambulance sees a bus 40 m ahead of him after 20 seconds the bus is 60 meter behind.
If the bus is stationary, then the total distance traveled by ambulance will be
 40m + 60m = 100m
Thus the velocity of the ambulance with respect to the bus will be
100/20 = 5 m/s
Also given that the velocity of the ambulance is
30km/h = (30x1000) / (60x60)
30km/h = 8.3 m/s
Substituiting all these values in equation (1), we get:
5 = 8.3 - y
y = 8.3 - 5
y = 3.3
which shows that the velocity of the bus is 3.3 m/s or 11.88 km/h
Hope it will help you.