Question

What work is said to be done to increase velocity of a car from 15km/hr to 30km/hr, if the mass of the car is 1000kg?

Answer 1

Answer:

26041.7

Explanation:

M = 1000 kg 

u = 15 km/h = 50/12 m/s

v = 30 km/h = 100/12 m/s

Work done = change in K.E.

K.E. = 1/2 mv² = 1/2 * 1000 * 50/12 * 50/12 = 8680.5 J

K.E. = 1/2 mv² = 1/2 * 1000 * 100/12 * 100/12 = 34722.2 J

34722.2 - 8680.5 = 26041.7 J

Hence work done = 26041.7

Answer 2

Answer:

52.08 kj

Explanation:

30 km/h = 25/3 m/s

work  done = m(v2² - v1²)/2 = 10³(625/9 - 625/36) = 10³×625/12 = 52.08 kj