When a train starting from rest is uniformly accelerating, a plumb bob hanging from the roof of a compartment is found to be inclined at an angle of $45^{0}$ with the vertical. The time taken by the train to travel a distance of 1/2 km will be nearly

7 s

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10 s

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15 s

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25 s

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Solution

The correct option is A 10 s
Taking, $g = 10 m / s^{2}$ ,
Since the bob makes a $45^{0}$ angle with vertical, total force (including pseudo force), and hence in vertical direction equals that of horizontal direction.
$m g = m a$
$a = g = 10 m / s^{2}$
$s = \frac{1}{2} a t^{2} = \frac{1}{2} k m$
$10 m / s^{2} \times t^{2} = 1000 m$
$t^{2} = 100$
$t = 10 s$

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When a train starting from rest is uniformly accelerating, a plumb bob hanging from the roof of a compartment is found to be inclined at an angle of 450 with the vertical. The time taken by the train to travel a distance of 1/2 km will be nearly

The correct option is A 10 sTaking, g=10 m/s2,Since the bob makes a 450 angle with vertical, total force (including pseudo force), and hence in vertical direction equals that of horizontal direction.mg=maa=g=10 m/s2s=12at2=12 km10 m/s2×t2=1000 mt2=100t=10 s

When a train starting from rest is uniformly accelerating, a plumb bob hanging from the roof of a compartment is found to be inclined at an angle of $45^{0}$ with the vertical. The time taken by the train to travel a distance of 1/2 km will be nearly