Shortcut Trick
Since the buses move at right angles, the distance between them is the hypotenuse of a right-angled triangle.
Resultant Speed = √(482 + 362) = √(2304 + 1296) = √3600 = 60 km/h.
Convert speed to m/s: 60 × (5/18) = 50/3 m/s.
Distance after 15 seconds = Speed × Time = (50/3) × 15 = 50 × 5 = 250 m.
∴ The correct answer is 250 m.
Alternate Method
Given:
Speed of Bus 1 (S1) = 48 km/h
Speed of Bus 2 (S2) = 36 km/h
Time (t) = 15 seconds
Formula Used:
Distance = Speed × Time
Conversion: 1 km/h = 5/18 m/s
Hypotenuse (H) = √(Base2 + Perpendicular2)
Calculations:
⇒ Speed of Bus 1 in m/s = 48 × (5/18) = 40/3 m/s
⇒ Distance covered by Bus 1 (D1) = (40/3) × 15 = 200 m
⇒ Speed of Bus 2 in m/s = 36 × (5/18) = 10 m/s
⇒ Distance covered by Bus 2 (D2) = 10 × 15 = 150 m
⇒ Distance between buses = √(D12 + D22)
⇒ Distance = √(2002 + 1502)
⇒ Distance = √(40000 + 22500) = √62500
⇒ Distance = 250 m
∴ The correct answer is 250 m.
Additional Information
Pythagorean Triplets
Sets of three integers like (3, 4, 5) satisfy a2 + b2 = c2. Scaling them (30, 40, 50) or (150, 200, 250) helps solve geometry problems instantly.
Unit Conversion
To convert km/h to m/s, multiply by 5/18. To convert m/s to km/h, multiply by 18/5.
Perpendicular Motion
When two objects move perpendicularly, their relative distance is calculated using the Pythagoras theorem based on the linear distance covered by each.