Keo Easy
Physics help plz!! easy 10 points! =]?
A roller coaster (403 kg) moves from A (3.31 m above the ground) to B (25.1 m above the ground). Two non-conservative forces are present: friction does -2.76 x 104 J of work on the car, and a chain mechanism does +5.25 x 104 J of work to help the car up a long climb. What is the change in the car's kinetic energy KEf - KEo from A to B?
Let the initial Kinetic Energy of the roller coaster is KE(o) & the final is KE(f)
Net Work done(Wnet) = 5.25 x 10^4 - 2.76 x 10^4 = 2.49 x 10^4 J
Work done to increase the PE (Wpe)= mg x delta h
=>Wpe = 403 x 9.8 x (25.1-3.31) = 8.6 x 10^4 J
As Wpe >Wnet
=>KE(o) > KE(f)
=>KE(f) - KE(o) = 2.49 x 10^4 - 8.6 x 10^4 = -6.11 x 10^4 J
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