Question

Q.7. A train travels with a speed of 60 km - from station A to
station B and then returns back with a speed 80 kmh from station
B to station A. Find : (i) the average speed, and (ii) the average
velocity of train.​

Answer 1

Answer -

1. Average speed = Total distance/Total time

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As the distance covered by train is same

Time taken by boy from home to school

$t_1 = \frac{s}{v_1}$

$t_2 = \frac{s}{v_2}$

$v_{avg} = \frac{s + s}{t_1 + t_2}$

$v_{avg} = \frac{2s}{ \frac{s}{v_1} + \frac{s}{v_2} }$

$v_{avg} = \frac{2v_1v_2}{v_1 + v_2}$

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$V_1 = 60 km/hr$

$V_2 = 80 km/hr$

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Substituting the value -

$v_{avg} = \frac{2 \times 80 \times 60}{60 + 80}$

$v_{avg} = \frac{9600}{140} = 68.57 km/hr.$

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2. Average velocity =

Total Displacement/Total time.

As the train reaches the starting point again , displacement equals to 0.

Average velocity = 0.

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Thanks

Answer 2

Answer:

Heya✌️☺️♥️

Explanation:

✏️Let the distance A and B be x km

Speed while going =60 kmph

∴ time required to go =60xhr

Speed while returning =80 kmph

∴ time required to return =80xhr.

∴ total time required =(60x+80x)hr=2407xhr.

And, total distance travelled =2x km

∴Average velocity=2407x2xkmph=68.57kmph

✒️Hope it helps♥️☺️✌️...