A box of mass 150 kg is prevented from sliding down the slope by a force,F, of 100 N acting at 40° to the rough inclined plane as shown. The plane isinclined at 35° to the horizontal and the coefficient of static friction betweenthe box and the surface is 0,7.

Draw a labelled free-body diagram showing all the forces acting onthe box. Calculate the component of the weight parallel to the inclined plane. Calculate the magnitude of the frictional force that is acting on thebox. The size of force F is slowly reduced from 100 N until the box is about to slide. Calculate the minimum value of the force F for the box to remain atrest.

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