F.4 physics

xtina

2010-04-16 6:38 am

an astronaut of mass 80 kg sits in a centrifuge machine and is brought into uniform circular motion as the arm of the machine rotates. The arm is 10m long and the astronaut experiences an acceleration of 6.5g.

a) find the centripetal force needed by him. What force provides this centripetal force?

b)Find his angular speed, linear speed and period.

c) if the angular speed of the machine is raised to twice the value in (b), what would be the acceleration felt by the astronaut? Give answer in terms of g.

回答 (1)

Prof. Physics

2010-04-16 9:16 am

✔ 最佳答案

a. Centripetal force = ma = (80)(6.5)(10) = 5200 N

The tension in the arm of the machine provides the centripetal force.

b. By F = mrw^2

5200 = (80)(10)w^2

Angular speed, w = 2.55 rads^-1

By v = rw

Linear speed, v = (10)(2.55) = 25.5 ms^-1

Period, T = 2pi / w = 2pi / 2.55 = 2.46 s

c. By a = rw^2

If the angular speed w is doubled, then the acceleration will become four times as before.

So, the acceleration will be 26 g

參考: Physics king

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