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physics help, could someone show me how to solve these? --problems regarding circular motion, and friction--?
here is the problem
At the instant shown the car is travelling at a constant speed of 85 km/hr at the crest of a hill having a circular arc profile of radius R = 190 m. Assume the driver's mass of 90 kg is entirely supported by a bathroom scale (yes, the driver is sitting on a bathroom scale!?!?). Determine the force in N exerted on the bathroom scale at the instant shown.
Hard braking 'locks' all wheels of the car in P9 above at the crest of the hill at the instant shown. Determine the absolute value of the acceleration in m/s/s if the COF between pavement and tires is 0.82; the speed at braking is 85 km/hr; and the circular arc radius R = 190 m.
3 Answers
- TechnobuffLv 75 years agoFavorite Answer
Even this assumes "instant shown" is crest of hill.
(85/3.6) = tangential V of 23.6m/sec.
Centripetal acceleration = (v^2/r) = (23.6^2/190) = 2.93m/sec^2.
Net acceleration acting on driver = (g - 2.93) = (9.8 - 2.93) = 6.87m/sec^2.
Scale reading = (ma) = (90 x 6.87) = 618.3N.
Rest cannot be done without diagram.
- Anonymous5 years ago
Show me the instant you are talking about?
