Question

9. A bicycle is to travel on a track with a length of 12 km. (a) The bicycle travels half of the total length at 10 km/h and the other half of the length at 30 km/h. (The transition fron one speed to the other is instantaneous (i.e., the velocity-versus-time graph is discontinuous at that transition point).) Determine the bicycle's average speed and its total travel time. (b) Instead, the bicycle travels this length at 10 km/h during half of the total time of travel, and at 30 km/h during the remaining half of the total time of travel. (The transition from one speed to the other is instantaneous (i.e., the velocity-versus-time graph is discontinuous at that transition the bicycle's average speed, its total travel time, and the length traveled in each leg of the trip.

Answer 1

(a) when distance covered are Equal, then Average speed theta variant = 2 theta variant_1 theta variant_2/theta variant_1 + theta variant_2 = 2 times 10 times 30/10 + 30 = 15 km/h travel time = 6/10 + 6/30 = 6/10[1 + 1/3] = 6 times 4/10 times 3 = 40/5 times 60 = 48 min (b) when Time intervals are Equal Then Avg speed = theta variant_1 + theta variant_L/2 = 10 + 30/2 = 20 km/h total time = 12/20 h = 3/5 times 60 = 36 min d_1 = 10 times 18/60 = 3 km d_2 = 30 times 18/60 = 9 km