Vivax Solutions

A Passport to Intelligent Realm

Friction - take g = 10 ms-2

  1. The mass of an object is 10kg and has the shape of a solid cuboid.The coefficient of friction of the surface is 0.3. Find the force of friction, if it is placed on,
    • The smallest surface
    • The largest surface.
  2. The mass of an object is 4kg and is placed on a rough horizontal plane. It is raised until the object is about to slide down the plane. If the angle at this stage is 300 to the horizontal, find the coefficient of friction between the object and the plane and prove it is independent of the mass of the object.
  3. The mass of an object is 5kg and is placed on a plane and raised slowly upwards. The angle between the plane and the horizontal is 300, when it is about to slide down. If the plane is raised by 150more, find the minimum external force needed to keep it in balance.
  4. A body weighing 10kg is on the point of slipping down a plane which is inclined at 200to the horizontal. What force parallel to the plane will just move it up the plane?
  5. A uniform rod has a mass of 5kg. It is placed between a smooth wall and a rough surface so that it is just in balance. The reaction between the rod and the wall is 120N. Find the coefficient of friction between the rod and the rough floor. Find the reaction at the bottom of the rod as well.
  6. A toy car of mass 5kg is moving at a steady speed along a rough surface, which exerts a frictional force of 10N. Find the driving force of its engine. If it is increased to 20N, what will happen to the motion of the object? What new facts can you find about its motion?
  7. A book of mass 4kg is pressed against a wall by a force. Prove that this force should at least be 40N, to stop it from sliding down.
  8. Why is it easier to mop a floor by pulling it along the surface than by pressing it against and pushing on the surface?
  9. Friction is necessary evil. Do you agree? Explain giving suitable examples for both pros and cons.
  10. A ball that falls through a thick liquid gains a constant speed at one stage. Sketch distance-time, speed-time and acceleration-time graphs for the ball up until that stage.