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Newton's Laws & Universal Law of Gravitation Sample Problems

  1. What gravitational force exists between two 3 kg balls placed 7.25 m apart?
  2. A sphere weighing 9800 N and another sphere weighing 1960 N are separated by 4 m. What gravitational force exists between them?
  3. A 20 N force gives a stone an acceleration of 4 m/s2. What is the weight of the stone?
  4. A 5 kg rocket is acted upon by an upward force of 59 N due to the thrust produced by its engines. What is the rocket's weight? Draw the free-body diagram representing these forces. What is the net force? What acceleration does it cause?
  5. A rope attached to an 80 N wagon pulls it horizontally to the right with an acceleration of 0.5 m/s2. What is the mass of the wagon? What is the net force causing this acceleration?
  6. A 65 N boy sits on a sled weighing 52 N on a horizontal surface. The coefficient of friction between the sled and the snow is 0.012. What is the magnitude of the frictional force? The sled is pulled at constant speed by a rope held horizontally. What is the tension (the pull) in the rope?
  7. A 100 N force is applied to a 10 kg box to push it across a horizontal surface. A frictional force of 20 N exists. What is the acceleration of the box?
  8. An object weighing 40 N rests on a surface. The coefficient of friction between the surface and the object is 0.35. What is the frictional force between the object and the surface? A 20 N force is applied to pull the object horizontally. What is the magnitude of the net force? What is the acceleration of the box?
  9. A man pulls a 300 N object across a horizontal surface using a 100 N force applied at a 35° angle. What is the normal force? If the object is pulled with an acceleration of 2 ms-2, what is the coefficient of friction?
  10. A man pulls a 80 N object across a horizontal surface using a 50 N force applied at a 25° angle. What is the normal force? If the coefficient of friction is 0.3, what is the acceleration of the object?
  11. A man pushes a 80 N object across a horizontal surface using a 50 N force applied at a 25° angle. What is the normal force? If the coefficient of friction is 0.3, what is the acceleration of the object?
  12. A 10 N object rests on a 10° incline. What is the normal force? What is the parallel force? A 10 kg object rests on a 10° incline. What are the normal and the parallel forces?
  13. A 5 N block slides down a 20° incline at constant speed. What is the frictional force?
    14. A 75 kg box slides down a 25° incline at constant speed. What is the fricitonal force?
  14. What force is needed to push a 15 N object up a 20° incline at constant speed when the coefficient of friction is 0.30?
  15. What is the coefficient of friction if a 50 N force is needed to push a 5 kg object up a 25° incline at constant speed?
  16. What is the acceleration of a 20 N object which slides down a 35° incline when the coefficient of friciton is 0.4?
  17. What is the coefficient of friction if a 40 N objbect slides down a 20° incline with an acceleration of 2 m/s-2?
  18. Find the tensions in the cables shown.

    drawing for problem 8

  19. Find the tensions in the cables shown.

    drawing for problem 9

  20. A man pulls a 300 N object across a horizontal surface using a 100 N force applied at a 35° angle. What is the normal force? If the object is pulled with an acceleration of 2 ms-2, what is the coefficient of friction?
  21. A man pulls a 80 N object across a horizontal surface using a 50 N force applied at a 25° angle. What is the normal force? If the coefficient of friction is 0.3, what is the acceleration of the object?
  22. A man now pushes a 200 N object across a horizontal surface using a 100 N force applied at a 35° angle. What is the normal force? If the object is pulled with an acceleration of 2 ms-2, what is the coefficient of friction?
  23. A man pushes a 80 N object across a horizontal surface using a 50 N force applied at a 25° angle. What is the normal force? If the coefficient of friction is 0.3, what is the acceleration of the object?

    24. Newton's Laws Notes

    Newton's Laws Homework