Circular Motion and Universal Gravitation Practice


  1. Mary is swinging a tennis ball duct-taped to the end of a 0.25m long string. Why? I don't know why. Mary is weird. Stop asking questions. Anyway, the ball has a mass of 0.05kg and it makes one rotation every 0.6s. What is the tension in the string? (1.37N)
  2. What is the force due to gravity between a 500kg object and a 250kg object separated by a distance of 0.01m? (0.08N)
  3. A car is traveling around a circular track at 10m/s. If the track has a radius of 50m, what is the period of the car? (31.4s)
  4. The sun has a mass of 2.0e30kg and the earth has a mass of 5.97e24kg. They are separated by an average distance of 1.5e11m. What is the force due to gravity between the sun and the earth. (3.54e22N)
  5. Using your answer from #4, what is the orbital period of the earth in days? (You should know this answer)
  6. Once again that weirdo Mary is swinging stuff tied to the end of cords. This time it's a sack of potatoes tied to the end of an electrical cord that she found in a vacant lot behind the C-Town in Newark, but I digress. Anyway, the sack of potatoes has a mass of 50kg and a tangential velocity of 5m/s. The cord is 1.25m long. What is the period of the sack of potatoes? (1.57s)