Attempt 1 of Unlim Points Available: 1 Assignment Policy Spi Time Spent 00:00:35

Question

Attempt 1 of Unlim Points Available: 1 Assignment Policy Spi Time Spent 00:00:350 Q 11: Two cars, A and B, travel in opposite directions along a straight road. A dog observes from the roadside. Car A has a speed of 29.9 km/h and car B has a speed of 31.8 km/h The positive direction is indicated in the figure. Study this topic calculate the relate vel DE a) What is the velocity of car B relative to the dog? m/s b) What is the velocity of car B relative to car A? fthe cars are initially separated by a distance of 0.12 km, how long will it take until 0 Information they are separated by 1.04 km?

Explanation / Answer

Given

speed of car A v1 = 29.9 km/h = 8.305 m/s (x kmph*5/18 = y m/s)

speed of car B v2 = 31.8 km/h = 8.833 m/s

car A moving in the -ve direction

car B moving in the +ve direction

a) the dog is at rest and observing the cars

velocity of car b relative to dog is V2 = 8.833 m/s

b) as the cars are moving in the opposite directions then the relative velocity of the cars is

V = V1+V2 = 8.305+8.833 m/s = 17.138 m/s

c) initially the cars are separted by 0.12 km = 120 m

time taken by them if the separation between them is 1.04 km = 1040 m

so the distance they should travel furthur is 1040-120 m = 920 m

let time taken by car A to cover a half of the distance is t1 = 460/8.305 s = 55.388 s

time taken by the car b to cover remainign 460 m is t2 = 460/8.833 s = 52.077 s

so total time T is = 55.388 + 52.077 s = 107.465 s

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