A 2000 kg car has been traveling in a roundabout for 25 minutes in a perfectly circular path with a speed of 19 m/s. (The radius of the circular path is 31 m.)
a. Determine the magnitude of the force maintaining the uniform circular motion of the car.b. Describe and explain in complete detail (using physics terms and ideas) what makes it possible for the car to travel in the circular path. Include in your description and explanation the applicationof both Newton’s First Law and Newton’s Third Law to the situation described in this problem.c. Explain, in detail, how centrifugal force is related to the situation described above.Hints: a. Recall that F = ma. b. Please be very thorough in your explanation. c. Don’t forget the “trick” I mentioned in the lecture on Newton’s Laws for, how to never get this type of question wrong.
- NCSLv 71 month agoFavourite answer
a. centripetal F = mv²/r
When I plug in your m, v and r I get F = 2.3E4 N
or 23 kN
b. The centripetal force is a "pseudoforce" in that it can't be shown on the free body diagram. What can be shown for YOUR diagram is the friction force that keeps the car from sliding outward. You might say that friction provides the centripetal force.
Newton's First of course says that a car (and its occupants) would move in a straight line unless acted on by an external force. Such an external force acts on the car (friction). That force acts indirectly on the passengers (through, say restraint systems or the doors or friction with the seat), and so the occupants "feel" this tendency to keep moving straight.
Newton's Third deals with action/reaction pairs. The car pushes radially outward on the road with the same force that the road pushes radially inward on the car.
c. I wasn't at your lecture, so I am not aware of any "trick" that might be employed.
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