Numerical – Kinetic Energy
Calculate the work required to be done to increase the velocity of an object from 20 km/hr to 40 km/hr, if the mass of the object is 40 kg.
We know that the S.I. unit of velocity is m/s, hence we need to convert the given velocities into m/s.
Initial Velocity
𝒖 = 𝟐𝟎 × ( 𝟏𝟎𝟎𝟎 )/𝟔𝟎×𝟔𝟎
u = 5.55 m/s
Final Velocity
v =𝟒𝟎 × ( 𝟏𝟎𝟎𝟎 )/𝟔𝟎×𝟔𝟎
v = 11.1 m/s
Initial Kinetic Energy
K.E. (initial) = (𝒎×𝒖𝟐)/𝟐
K.E. (initial) = 616 Joules
Final Kinetic Energy
K.E. (final) = (𝒎×𝒗𝟐)/𝟐
K.E. (final) = 2469 Joules
Work Done = Final Kinetic Energy – Initial kinetic energy