NEET2025PhysicsMotion in One DimensionActual
Two 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 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 bus
Options
- A9 ~min , 40 ~km / h
- B25 ~min , 100 ~km / h
- C10 ~min , 90 ~km / h
- D15 ~min , 120 ~km / h
Correct answer
D. 15 ~min , 120 ~km / h
Step-by-step solution
t ₁=30 ~min = 1 2 hr aligned t ₂ & =10 ~min = 1 6 hr ~V _ B & = Speed of Bus V _ S & = Speed of scooty (girl) aligned (Same direction) (Opposite direction) aligned & d= (V_B-V_S ) t₁= (V_B+V_S ) t₂ & (V_B-60 ) 1 2 = (V_B+60 ) 1 6 & 3 V_B-180=V_B+ 60 & 2 V_B=240 & V_B=120 ~km / hr aligned Distance = ( V _ B - V _ S ) t ₁ aligned & D =(120-60) 1 2 =30 ~km & t = d ~V _ B = 30 120 = 1 4 hr =15 ~min aligned