Question

a car travels from stop A to B with a speed of 30km/h and returns back to A with a speed of 50km/hr. Find displacement and distance travelled by the car. what is the average speed of the car

Answer 1

Let the distance from A to B be x.

Then displacement of the car when it comes back to the same position is zero.

Distance travelled is 2x.

Time taken by the car when it moves from A to B is given by

t1 = Distance/Speed = x/30

Time taken by the car when it moves from B to A,

t2 = Distance/Speed = x/50

Total distance = 2x

Total time

= t1 + t2

= x/30 + x/50

= (5x + 3x)/150

= 8x/150

So, Average speed

= Total distance/Total time

= 2x/(8x/150)

= 37.5 km/hr

Answer 2

Answer:

Let the distance from A to B be x.

Then displacement of the car when it comes back to the same position is zero.

Distance travelled is 2x.

Time taken by the car when it moves from A to B is given by

t1 = Distance/Speed = x/30

Time taken by the car when it moves from B to A,

t2 = Distance/Speed = x/50

Total distance = 2x

Total time

= t1 + t2

= x/30 + x/50

= (5x + 3x)/150

= 8x/150

So, Average speed

= Total distance/Total time

= 2x/(8x/150)

= 37.5 km/hr