A single frictionless roller-coaster car of mass m = 750. kg tops the first hill with speed v = 15.0 m/s at height h = 20.0 m as
shown. (show work)
Find the speed of the car at points A, B and C. Show all your work. (Hint: to start, find the total mechanical energy at the top of the first hill.)
Find the speed of the car at points A, B and C. Show all your work. (Hint: to start, find the total mechanical energy at the top of the first hill.)
1 answer:
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Answer:
a. 79.1 N
b. 344 J
c. 344 J
d. 0 J
e. 0 J
Explanation:
a. Since the crate has a constant velocity, its net force must be 0 according to Newton's 1st law. The push force by the worker must be equal to the friction force
on the crate, which is the product of friction coefficient μ and normal force N:
Let g = 9.81 m/s2
b. The work is done on the crate by this force is the product of its force and the distance traveled s = 4.35
c. The work is done on the crate by friction force is also the product of friction force and the distance traveled s = 4.35
This work is negative because the friction vector is in the opposite direction with the distance vector
d. As both the normal force and gravity are perpendicular to the distance vector, the work done by those forces is 0. In other words, these forces do not make any work.
e. The total work done on the crate would be sum of the work done by the pushing force and the work done by friction