Question

An auto travels at a rate of 25 km/hr for 4 minutes, then at 50 km/hr for 8 minutes, and finally at 20 km/hr for 2 minutes. find the total distance covered in km and the average speed for the complete trip in m/s.

Answer 1

We know that the formula for calculating distance is:

distance d = velocity v * time t

 

Calculating for each interval:

 

1: 25 km/hr for 4 minutes

d1 = (25 km / 60 min) (4 min) = 1.67 km

 

2: 50 km/hr for 8 minutes

d2 = (50 km / 60 min) (8 min) = 6.67 km

 

3: 20 km/hr for 2 minutes

d2 = (20 km / 60 min) (2 min) = 0.67 km

 

The total distance covered is:

d = d1 + d2 + d3

d = 1.67 + 6.67 + 0.67

d = 9 km

 

The average speed is:

s = 9 km (1000 m / km) / (14 min * 60 s / min)

s = 10.72 m / s