F6 Physics - Circular Motion*2

[匿名]

2010-05-22 1:24 am

4. A car of mass 1500kg travels on a circular road at 50m from the centre.The speed of the car is 12ms^-1.

(a) Find the centripetal force needed by the car.
(b) If the road is level,find the friction acting on the car.You may neglect the friction in the direction of motion.
(c) If the road is banked at 5^o to the horizontal ,find the friction acting on the car.Is it greater or smaaler than that in (b).

6. A motorcyclist is turning a circular corner of radius 20m at a constant speed in a race.
(b) The total mass of the motorcycle and the motorcyclist is 180 kg , and the max. friction that can be developed from the track is 0.5 times the normal reaction.Find the max. speed at which the motorcyclist can turn the corner without slipping/

回答 (1)

Chau

2010-05-22 1:34 am

✔ 最佳答案

4.
a)
F=mv^2/r
F=1500*144/50
F=4320N
b)f=4320N
c)
Ncos5=mg
N=15000/cos5
Nsin5+fcos5=mv^2/r
15000tan5+fcos5=1500*144/50
f=3019N
Which is greater than the result in b.

6.
b)
F=mv^2/r
0.5mg=mv^2/r
0.5*180*10=180*v^2/20
v=10m/s

2010-05-21 17:55:08 補充：
Which is greater than the result in b should change to Which is smaller than the result in b

參考: Lucas Chau

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