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physics help, please help me solve this...?
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 62 km/hr; and the circular arc radius R = 84 m
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the question before it
At the instant shown the car is travelling at a constant speed of 62 km/hr at the crest of a hill having a circular arc profile of radius R = 84 m. Assume the driver's
of 50 kg is entirely supported by a bathroom scale (yes, the driver is sitti only need the first one solved, please show me how!
ing on a bathroom scale!?!?). Determine the force in N exerted on the bathroom scale at the instant shown. answer 313.95
2 Answers
- ?Lv 75 years agoFavorite Answer
62km/h * 1m/s / 3.6km/h = 17.2 m/s
scale reading W = m(g - v²/r)
W = 50kg * (9.8m/s² - (17.2m/s)² / 84m) = 50kg * 6.27m/s² = 313 N √√√
At the moment of braking:
the velocity is still (momentarily) 17.2 m/s, so the vertical acceleration is still the same at 6.27 m/s².
Braking induces a friction force
Ff = µ*Fn = µ*m*(g - a) = 0.82 * m * 6.27m/s² = m * 5.14m/s²
The resulting acceleration is
a = Ff / m = 5.14 m/s² ◄
the magnitude of the braking acceleration
Now it's possible they want the magnitude of the TOTAL acceleration:
|a| = √(5.14² + 6.27²) m/s² = 8.11 m/s²
but I don't think so.
Hope this helps!
