5) A girl with 40kg mass is riding an 8 kg bicycle. At the top of the hill her speed is 6.0 m/s, and her speed triples at the bottom of the hill. The hill is 15.0 m high. What is the work done by the non conservative forces?

Work = 6912 joules

Explanation:

Non-conservative forces are dissipative forces such as friction or air resistance. These forces take energy away from the system as the system progresses, energy that you can't get back. These forces are path dependent; therefore it matters where the object starts and stops.

Total mass = 40 + 8 = 48kg

Initial speed u = 6 m/s

Final speed v = 3*initial

Final speed v = 3 * 6 = 18 m/s

Distance s = 15

Acceleration a is?

V² = U² + 2aS

18² = 6² + 2a*15

324 = 36 + 30a

324-36 = 30a

288 = 30a

288/30 = a

9.6 = a

Force = mass * acceleration

Force = 48*9.6

Force = 460.8N

Work = force*distance

Work = 460.8*15

Work = 6912 joules