Aims Problems Subject

Chapter 4: Rigid bodies. (III) – Problems


  1. A mass M = 120 kg hangs from a beam which is held by a cable.
    1. What is the tension T in the cable?
    2. Does the wall exert any force on the beam? Which one?
  2. A stone of mass 0.6 kg is forced to travel in a circle while it hangs from the ceiling, as shown in Figure. If the angle between the rope and the vertical is θ = 30º and the radius of the circle is r = 35 cm:
    1. What is the speed of the stone?
    2. What is the tension in the rope?
  3. A wheel of radius r = 80 cm has moment of inertia 10 kg m2. It is rotating around its central axis propelled by a rocket attached to a point on its outer rim. The rocket is expelling gas
    tangentially to the wheel, resulting in a constant force. Determine:

    1. The magnitude of the equivalent force, if we know that the wheel, starting from rest, reaches an angular speed of 1 rev/s in 6 s.
    2. The value of both tangential and normal acceleration in a point on the outer rim of the wheel.
    3. The angle that the total acceleration forms with the radius at that point.
    4. The time that the wheel takes to reach the same angular velocity, under the action of the same force, if we add a very thin ring of mass 5 kg around the outer rim.