4. PRELAB QUESTIONS
1. Looking down from a stationary tree branch, a merry-go-round spins in a counter-clock-wise direction with an angular velocity of 1 radian per second. A squirrel of mass 0.6 kg sits on the outer rim of the merry-go-round, at a radius of 4.0 meters.
a) What is the magnitude and direction of the vector ̐ω?
b) What is the magnitude and direction of the Coriolis pseudo-force as felt by the squir-rel?
c) What is the magnitude and direction of the centrifugal pseudo-force as felt by the squirrel?
2. Again, looking down from a stationary tree branch, a merry-go-round with a 1.2 meter radius spins in a counter-clockwise direction with an angular velocity of 1 radian per sec-ond. From your viewpoint, a bird of mass 0.4 kg flies in a straight line over the axis of the merry-go-round at a uniform speed of 3 m/s.
a) Draw the trajectory of the bird as seen from your stationary tree branch.
b) Draw the trajectory of the bird as seen from an observer on the merry-go-round.
c) Consider three instants:
i. When the bird first crosses the outer edge of the merry-go-round;
ii. When the bird crosses the center of the merry-go-round;
iii. When the bird finally crosses the outer edge of the merry-go-round.
For each of the three moments, as seen by an observer on the merry-go-round, il-lustrate the direction of the centrifugal pseudo-force that seems to act on the bird. At what point is the centrifugal pseudo-force 0? You may use your sketch from part (b).
d) For instant (i), also illustrate on your sketch the direction of the Coriolis pseudo-force acting on the bird (as seen by an observer on the merry-go-round). Remember that the bird has both a radial velocity relative to the merry-go-round, as well as a tangential velocity. For both these components, you will have to determine the direction of the corresponding Coriolis force component.