Can you determine the braking force required to slow the train of - ProProfs Discuss

# Can you determine the braking force required to slow the train of cars by this amount? At the end of the Shock Wave roller coaster ride, the 6000-kg train of cars (includes passengers) is slowed from a speed of 20 m/s to a speed of 5 m/s over a distance of 20 meters.

A. 65 657 N
B. 56 250 N

This question is part of Lesson 2 : The Work - Energy Theorem

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w = fd = 1/2 m ( v final ^2 - v intial ^2 )
-1125000 = 20 d
d = -56250
then d = 56250n   Reply #### John Smith

John Smith  Answered on Nov 12, 2016

56 250 N

Initially: PE = 0 J (the cars height is zero) KE = 0.56000(20)^2 = 1 200 000 J Finally: PE = 0 J (the cars height is zero) KE = 0.56000(5)^2 = 75 000 J The work done is F 20 cos 180 = -20F Using the equation, TMEi + Wext = TMEf 1 200 000 J + (-20F) = 75 000 J Using some algebra, it can be shown that 20F = 1 125 000 and so F = 56 250 N   Reply Search for Google images Select a recommended image
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