Mass of the cyclist together with the bike(m) = 90 kg.
Initial Speed(u) = 60 km/hr.
= 60 × 5/18 [Changing into m/s.]
= 5/3 m/s.
Final Speed(v) = 12 km/hr.
= 12 × 5/18 [Changing into m/s.]
= 10/3 m/s.
Increases in Kinetic Energy = 1/2 × m(v² - u²)
= 1/2 × 90 × [(10/3)² - (5/3)²]
= 45 × [100/9 - 25/9]
= 45 × [75/9]
= 5 × 75
= 375 J.
Hence, the increases in the kinetic energy of the cyclist is 375 J.
