what do you mean by work give an example of negative work done what is work to be done increase the velocity from 18 km per hour to 90 km per hour the mass of the care is 2000 kg
Answers
What work can be done to increase the velocity from 18km/hr to 19km/hr if the mass of a car is 2,000kg?
Given:
Initial velocity u=18km/h=5m/s
Final velocity v=19km/h=5.278m/s
Mass of the car m=2000kg
To find:
Work done in increasing the velocity of the car from uto v.
Solution:
Let Wbe the work and ΔK=Kf−Kibe the increase in kinetic energy. (Here Kfand Kiare the final and initial kinetic energies respectively.)
From the work-energy theorem, we know that the work done will equal the change in kinetic energy. That is W=ΔK.
Kinetic energy of a particle K=12mv2
Hence, the increase in kinetic energy can be found by subtracting the initial kinetic energy from the final kinetic energy
ΔK=12mv2−12mu2
=> 12m(v2−u2)
= 12(2000)(5.2782−52)
= 5714.5682
= 2854.28J.
Hence the work done in increasing the velocity of a car of mass 2000 kg from 18 km/h to 19 km/h is 2854.28J.