OnlineCBT
Physics · PYQ NEET UG 2025
हिन्दीTwo cities X and Y are connected by a regular bus service with a bus leaving in either direction every \( T \) min. A girl is driving scooty with a speed of \( 60\text{ km/h} \) in the direction X to Y notices that a bus goes past her every \( 30 \) minutes in the direction of her motion, and every \( 10 \) minutes in the opposite direction. Choose the correct option for the period \( T \) of the bus service and the speed (assumed constant) of the buses.
Correct answer · Option 4
15 min, 120 km/h
Explanation
Using relative velocity equations for interval between buses: \( T_1 = \frac{T}{1 - v_g/v_b} = 30 \) and \( T_2 = \frac{T}{1 + v_g/v_b} = 10 \) with \( v_g = 60 \). Solving gives \( T = 15 \) min and \( v_b = 120\text{ km/h} \).
