Question

Q1 what is the work to be done to increase the velocity of a car from 30 km h-1 to 60 km h-1 if the mass of the car is 1500 kg

Q2 what is kinetic energy of an object

Answer 1

a = 60 - 30 = 30 km^2/hour

W = mas

W = 1500 * 30 * s

v^2 = u^2 + 2as

60^2 - 30^2 = 30 s

2700/30 = s

s = 90m

W = 1500*30*90

W = 4050000 joule

Answer 2

Work done = Change in Kinetic Energy

The kinetic energy of an object of mass m and moving with velocity v is given by

K.E=

$\frac{1}{2} m {v}^{2}$

Now consider a body of mass m and with initial and final velocities u and v.

The Work done by that object is given by

W=

$\frac{1}{2} m( {v}^{2} - {u}^{2} )$

Now given

m=1500Kg

u= 30kmph

$u = 30 \times \frac{5}{18} m {s}^{ - 1} = \frac{25}{3} m {s}^{ - 1}$

v= 60kmph

$v = 60 \times \frac{5}{18} m {s}^{ - 1} = \frac{50}{3} m {s}^{ - 1}$

Now the Work done is

$\frac{1}{2} (1500)( {( \frac{50}{3}) }^{2} - {( \frac{25}{3}) }^{2} ) \\ \\ = 750 \times \frac{1}{9} (2500 - 625) \\ \\ = 750 \times \frac{1}{9} \times 1875 \\ \\ = 750 \times 625 \times \frac{1}{3} \\ \\ = 468750 \times \frac{1}{3} \\ \\ = 156250 \: Nm$

Therefore Work done is

156250 Nm

hope it helps