Two cars start from the same place at the same time at right angles to each other. Their speeds are 54 km/hr and 72 km/hr, respectively. After 20 seconds the distance between them will be:

500 m

54 km/h = 54 × \(\frac{5 }{18}\)

= 15  m/sec

72 km/h = 72 × \(\frac{5 }{18}\)

= 20  m/sec

Distance covered by 1st car = 15 × 20 = 300 m

Distance covered by 2nd car = 20 × 20 = 400 m

Distance between two cars ,

H² =  P²  +  B²

H² =  300²  +  400²

H = 500 m