IB Physics Topic A Tutorial Sheet : Block on a Wedge

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A tutorial sheet on Topic A SL/HL that practices force concepts. These are “show that” questions that require a labelled diagram and all steps shown to receive full marks.

A block of mass m is placed on the hypotenuse of a smooth wedge of mass M and base angle 𝜃 that rests on a smooth horizontal surface.

The wedge is held at rest by a horizontal force F acting perpendicular to its vertical side.

  1. Show that the acceleration of the block of mass m as it slides down the wedge is gsin𝜃.
  2. Show that the normal force between the sliding mass and the wedge is mgcos𝜃.
  3. Show that the normal force between the horizontal surface and the wedge is g(M+m cos2𝜃)
  4. Show that F = mgcos𝜃 sin𝜃.

The block stays at rest relative to the wedge when a new force F acts perpendicular to the vertical side of the wedge.

  1. Show that the acceleration of the block is the same as the acceleration of the wedge.
  2. Show that the normal force between the block and the wedge is N = mg/cos𝜃.
  3. Show that the resultant force acting on the block is Nsin𝜃.
  4. Show that the acceleration of the block is gtan𝜃.
  5. Show that F = (M+m)gtan𝜃.