## Friday, 5 September 2014

### CIRCULAR MOTION PROBLEMS

CIRCULAR MOTION

(Take g = 9.8ms-2 )

1. Calculate the centripetal force in the following cases:
(a) a ball of mass 150 g is spun in a horizontal circle of radius 3m at 5 ms-1
(b) the Earth (mass 9x1024 kg) orbits the Sun once every year (3x107 s),  orbit  radius 1.5x1011 m
(c) an electron (mass 9x10-31 kg) orbits a nucleus in 1.6x10-16s, orbit radius 10-10 m

2. Calculate the angular velocity of an object that makes: (a) 25 revs per second
(b) 33.3 revs per second

3. An astronaut is trained in a centrifuge that has an arm of length 6m. If the astronaut can withstand an acceleration of 7 g :
(a) what is the maximum number of revs per second of the centrifuge (b) what is the maximum linear velocity of the astronaut .

4. A motorway interchange includes a smooth bend of radius 23 m. At what angle must it be banked so that a car can take the bend in an umpowered state at 20 ms-1?

5. A pilot in a stunt plane loops the loop in a vertical circle of radius 0.6 km at a constant speed of 250 km/hour. If the pilot has a mass of 75 kg calculate:
(a) the maximum resultant force on the pilot (b) the minimum resultant force on the pilot stating where in the loop each occurs

6. (a) Calculate the acceleration of a satellite orbiting the Earth at a distance of 42000 km from the its centre with an orbit time of 1 day (86400s).
(b) what might such a satellite be used for?

7. A fairground ride consists of cars suspended from wire 5 m long. If the ride rotates so that the wires make an angle of 25° with the vertical calculate: