# Answer on Mechanics | Relativity Question for Som

Question #12298

A trolley of mass 20 kg carries 16 kg grain and moves on a horizontal smooth and straight track at 20m/s.If the grain starts leaking out of a hole at the bottom at time t=0 s at the rate of .5 kg/s,what will be the speed of trolley at t=22s?

Expert's answer

Mass of leaked grain: 22 s *0.5 kg/s = 11 kg

After 22 seconds trolley carries mass of grain 16 kg - 11 kg = 5 kg

Total mass before the leakage m1 = 20 + 16 = 36 kg

Total mass after leakage m2 = 20 + 5 = 25 kg

From the momentum conservation law we have:

p1 = p2 or

m1*v0 = m2*v

Then the velocity after 22 seconds will be

v = v0*(m1/m2) = 20 m/s * (36 kg/25 kg) = 28.8 m/s

After 22 seconds trolley carries mass of grain 16 kg - 11 kg = 5 kg

Total mass before the leakage m1 = 20 + 16 = 36 kg

Total mass after leakage m2 = 20 + 5 = 25 kg

From the momentum conservation law we have:

p1 = p2 or

m1*v0 = m2*v

Then the velocity after 22 seconds will be

v = v0*(m1/m2) = 20 m/s * (36 kg/25 kg) = 28.8 m/s

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## Comments

shailendra05.05.2016 22:25Thank u very much

Assignment Expert06.08.2015 12:24Dear sundeep, thank you for your question. Look at the modified answer above.

sundeep06.08.2015 09:57what is the value 1.8..? mass/velocity...? can anyone explain the relationship used here..

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