The Gravity Study: Relation Between Centripetal Force and Rotation Frequency

Objective: The objective of the lab was to determine the relationship between centripetal force and the frequency of rotation.Theory: Circular motion is an accelerated motion that follows a circular path in which its speed is constant while the direction continually changes. This change in direction is caused by an external force, the centripetal force, which changes it towards the center of the circle rather than allowing it to continue on a linear path. The magnitude of the force is given by Fc=mv2/r. The velocity can be determined by multiplying the distance traveled by the frequency which is the inverse of the period, v=2rf. Combining the two, we get Fc=42f2mr, which represents the centripetal force. Equation 11, ML=42m/gf 2, is the equation for circular motion. Applying it to the lab, '42m/g' represents the ball’s mass affecting the frequency of revolutions. In the equation, ‘m’ is the only variable since the remainder of the terms are constants. The equation as a whole relates to the experiment by explaining the connection between centripetal force and frequency.

Procedure: For this lab, we placed a hooked mass of 100 gm at the end of the a string and whirled the racket ball above our heads while holding onto the string below the tube, keeping the path completely horizontal at a constant motion until we could let go of the string below the tube. We took note if there were any changes necessary in tension in order to keep the same horizontal path and radius after increasing the speed of the ball. The string used was 50 cm in length, with an alligator clip attached to it about 1 cm below the plastic to serve as a marker to keep a constant radius while whirling the ball. Upon completion of that, we hung a 100 gm hooked mass at the end of the string and began whirling it around while a partner measured the time it took the ball to swing through a fixed number of revolutions. To obtain the total time, we subtracted, making sure the difference between the second total time and the first total time was no greater than 2 seconds. Having completed the experiment with the 100 gm hooked mass, we conducted the same experiment again with a hooked mass between 50 gm and 100 gm. The same experiment was also conducted with a hooked mass between 100 gm and 300 gm. The final two experiments required changes in the lengths of the string, the first being between 30 and 50 cm, followed by a length between 50 and 70cm. For both, we used a 100 gm hooked mass. Finally, we determined the mass of the ball.

“Artificial” Gravity, Science and Technology Altered gravity or zero gravity can result in undesirable effects on the human body. For instance, loss of muscle volume and bone density in the legs, which makes them weaker, can occur as a result of prolonged weightlessness. This could eventually lead to loss of locomotor function in the legs due to a reduction in spinal cord excitability.1 Weakened bones also make astronauts more vulnerable since their bones can break easily in the case of an accident such as falling. A person’s vestibular system which provides sensory information about motion, equilibrium, and spatial orientation, can also be affected, not allowing an individual to be able to distinguish between up and down.2 A rotating space station could provide its occupants “artificial” gravity, hopefully eliminating all the problems mentioned previously. Its radius would have to be so large that ‘any difference in rotation rate between the feet and the head of the inhabitant would be negligible, and thus they will experience the sensation of gravity evenly throughout their bodies.’3 As the station spins, centrifugal force acts to pull the occupants to the outside which would simulate gravity.

A project like this, however, could be very challenging to conduct. A space station of the sort would have to be significantly large which only augments the expenses. It’s important to keep in mind that it costs approximately $1million per pound to lift an object into space.5Not only that, but the space station would have to be perfect being that the slightest asymmetry in the mass would be an obstacle.5 A gravity impulse generator is an innovative device which utilizes A Marx generator discharge through a superconducting emitter in a high magnetic field.6 The gravity impulse generator produces a non-diverging beam of force with properties similar to gravity waves. This device would be a good way to propel objects since it does not lose energy as a result of long distances. Also, it could be used to propel space crafts since it can discharge up to 5 million bolts.