Question

what is the work needed to be done to increase the velocity of a car from 30 kilometre per hour to 60 kilometre per hour if the mass of car is
1500 kg
​

Answer 1

Explanation:

m = 1500kg

u = 30 km/h = ($\frac{5}{18}$×30) m/s = $\frac{25}{3}$m/s

v = 60 km/h = ($\frac{5}{18}$×60) m/s= $\frac{50}{3}$m/s

E = m(v²-u²) = 1500×[$(\frac{50}{3})^{2}$-$(\frac{25}{3})^{2}$ ]

= 1500×($\frac{2500}{9}$-$\frac{1250}{9}$)

= 1500×$\frac{1250}{9}$

= 208333.3 J = 208.33kJ

Answer 2

Answer:

Work done is 156250 J.

Explanation:

Given,

The mass (m) of the car is 1500 kg.

Initial velocity of car = u = 30 km / hr = 30 * 5/18 = 25 / 3 m/s

Final velocity of car = v = 60 km / hr = 60 * 5/18 = 50/3 m/s

To find: The work to be done to increase the velocity of a car from

30 km h-1 to 60 km h^-1

Solution:

Initial kinetic energy = Ki = 1/2mu² = 1/2*1500*25/3 * 25/3 = 156250/3 J

Final Kinetic energy = Kf = 1/2mv² = 1/2*1500*50/3*50/3 = 625000/3 J

Work done can be given as change in Kinetic Energy,

i.e W = ΔK.E

or, W = Kf -  Ki

or, W = 625000/3 - 156250/3

or, W = 156250 J

Therefore, Work done is 156250 J.