Question

A body starts from rest and accelerates to attain
spped of 72 km h-¹ in 20s. Then it retards to come to rest after covering a distance of 80m. Calculate the acceleration as well as the retardation of the body.


qualified answers only​

Answer 1

Explanation:

• Initial velocity (u) = 0

Final velocity (v) = 72 km/h = 20 m/s Distance travelled = 80 m Acceleration = ?

Time taken = 20 seconds

Retardation = ?

We know that

• v - u = at

• 20-0= a × 20

• 20 = 20a

• a = 1 m/s^2

Retardation -:

• u = 20 m/s

• v = 0 (At last the body came at rest)

• s = 80 m

• We know,

• V^2u^2 = 2as

• 0 (20)^2 = 2 ×a × 80 -

• - 400 = 160 a

• -400/160 = a

Required answer:-

a = -2.5 m/s^2

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