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21. A car starts with velocity 10 m's and scalerates at rate 5 m/s? Find the finalvelocity when the car has travelled a distar ca 30 m

Answer»

Using relation

Vf - Vi = atVf - 10 = 5 * tt = (Vf - 10)/5

Now,S = Vi*t + 1/2 at^230 = 10*(Vf - 10)/5 + 1/2*5*[(Vf-10)/5]^2

30 = 2Vf - 20 + 5/2 *(Vf - 10)^2/25

30 = 2Vf - 20 + 5/2(Vf^2 + 100 - 20Vf)/25

30 = 2Vf - 20 + 1/10(Vf^2 + 100 - 20Vf)

50*10 = 20Vf + Vf^2 + 100 - 20Vf

Vf^2 = 500 - 100 = 400

Vf = 20

Therefore,Final Velocity = 20 m/s



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