A uniformly accelerated bus passes over a straight bridge of length 4.2 km. With what velocity should the bus enter the bridge in order to leave the bridge with a velocity of 29 metre per second in 4 minutes?
Please answer with correct step by step explaination.
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Answer:
The bus should enter with velocity 6 m/sec
Explanation:
given in question
length of bridge S = 4.2 km = 4200 m
final velocity at the end of bridge V = 29 m/sec
time taken t = 4 minutes = 240 sec
now first we find acceleration of bus by first equation of motion
v = u + at
a = (v - u ) / t
a = (29-u)/240 (1)
now second equation of motion
s = u t + 1/2 at²
put all values
4200 = 240 u + 1/2 ((29-u)/240) ×240×240
solving this
4200 = 240(u+ 29/2 + u/2)
105/6 = u/2 +29/2
105/6 - 29/2 = u/2
18/6 = u/2
3 = u/2
so
u = 6 m/ sec
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