7 A block of mass 4 kg is in equilibrium on a rough plane inclined at \(60 ^ { \circ }\) to the horizontal, as shown in Fig. 4. A frictional force of 10 N acts up the plane and a vertical string AB attached to the block is in tension.
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\caption{Fig. 4}
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- Draw a diagram showing the four forces acting on the block.
- By considering the components of the forces parallel to the slope, calculate the tension in the string.
- Calculate the normal reaction of the plane on the block.