Reality? • In reality, non-conservative forces cannot be ignored: friction really does act • Dissipative force is one that reduces the total mechanical energy • The total energy is conserved, it is just converted into useless forms (heat from friction) • KE1 + PE1 = KE2 + PE2 + Dissipative Force
Friction Most Common • Friction depends on the distance traveled • Wf = Ffd • KE1 + PE1 = KE2 + PE2 + Ffd
Example • A 1000kg roller coaster car starting from a height of 40m is found to reach a vertical height of only 25m on the next hill. If the total distance traveled was 400m . Find the force of friction acting on the car.