Question

30. The given graph shows the position versus time
graph of a car
What was the speed of the car during the entire
trip?
(A) 25 km/h (B) 50 km/h
(C) 100 km/h
(D) 125 km/h​

Answer 1

Answer:-

Given:-

Case 1:- (O to A)

• Distance covered = 20 km
• Time taken = 60 s

Case 2:- (A to B)

• Distance covered = 0 km (rest)
• Time taken = (90 - 60) s = 30 s

Case 3:- (B to C)

• Distance covered = (30 - 20) km = 10 km
• Time taken = (120 - 90) s = 30 s

Case 4:- (C to D)

• Distance covered = (10 + 10 + 10)km = 30 km
• Time taken = (210 - 120) s = 90 s

To Find:-

Avg. speed of the car during the trip.

____________...

We know,

Avg. speed = (Total distance covered)/(Total time taken)

∴ Avg. speed:-

[(20 + 0 + 10 + 30) km]/[210 s]

(See graph, total time taken for the trip shows is 210 s)

➵ [(60) km]/[(210) s]

➵ (60 • 1000 m)/(210 s)

➵ (60 • 100 m)/(21 s)

➵ (20 • 100m)/(7 s)

➵ (2.85 • 100m) s^-1

➵ 285m s^-1 ...(Ans. - Approx val.)

➵ 1026 km/h