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प्रश्न
A woman starts from her home at 9.00 am, walks with a speed of 5 km h–1 on a straight road up to her office 2.5 km away, stays at the office up to 5.00 pm, and returns home by an auto with a speed of 25 km h–1. Choose suitable scales and plot the x-t graph of her motion.
उत्तर
Time at which she leaves home for the office = 9 am.
Speed of the woman = 5 km h–1
Distance between her office and home = 2.5 km
Therefore, time taken to reach the office,
`"Time taken" = "Distance"/"Speed"`
=2.5/5 = 0.5 h = 30 min
Thus, the time she reaches at her office = 9.30 a.m.
It is given that she covers the same distance in the evening by an auto.
Time at which she leaves her office = 5 pm
Now, speed of the auto = 25 km/h
`"Time taken" = "Distance"/"Speed"`
=2.5/25 = 1/10 = 0.1 h = 6 min
Therefore, the time at which she reaches her home = 5.06 pm.
The suitable x-t graph of the motion of the woman is shown in the given figure.
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