Chapter 10

NCERT
Class 9
Science
Solutions
17. Calculate the work required to be done to stop a car 1500 kg moving at a velocity of 60 km/h?

Question:

Calculate the work required to be done to stop a car 1500 kg moving at a velocity of 60 km/h?

Answer:

u = 60 km/h

u = (60 x 1000)/(60 x 60)

u = 50/3 m/s

v = 0

m = 1500 kg

From the work-energy theorem the work done

W = Change in kinetic energy

W = 1/2 m(v2-u2)

W = 1/2 x 1500(02-(50/3)2)

W = -750 x 2500/9

W = = – 208333.3 J

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