Question

A bus moving with the velocity of 60km/hr brought to rest in20s by applying brakes. Find its retardation

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Answer 1

Given :

Initial velocity of the bus, u = 60 km/h

Final velocity of the bus, v = 0m/s

Time taken, t = 20 sec

To Find :

retardation of the bus.

Solution :

First of all we have to convert km/hr to m/s

1 km/hr = 5/18m/s

60km/hr = 60 × 5/18 = 16.66 m/s

as we are provided with initial Velocity, final velocity and time we can use 1st equation of motion .i.e.,

➠ v = u + at

by, substituting all the given values,

➠ 0 = 16.66 + (a)(20)

➠ -16.66 = 20a

➠ -16.66/20 = a

➠ a = - 0.83 m/s²${.}$

thus, the retardation of bus is - 0.83 m/s².

Remember !

If the speed is decreasing with time then accerlation is negative. The negative accerlation is called retardation.

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