6.4 M1 Homework

To Be Completed for Wednesday

1. a. A box of mass 5Kg is being pulled up a rough slope inclined at 30 degrees. The rope is inclined at an angle of 10 degrees to the slope. When the tension in the rope is 50 Newtons, the box is in equilibrium, about to slip up the plane. Calculate the coefficient of friction.
   
   

   b. If the tension in the rope is reduced to 30 Newtons, calculate the magnitude and direction of the friction, checking that it is not exceeding limiting friction.

   [7 marks]

2. A uniform plank of weight W Newtons is sticking out over a cliff. The plank is in a position so that 80% of the plank is on the land. When Alf (weight 50N) stands at the dangerous end of the plank, the plank is about to deliver him to his destiny. Alf gets off and the plank is then moved so that 65% of its length is on land. Bert (weight Y Newtons) then stands on the dangerous end and is about to be delivered to destiny. Find Y and W.
   

   [5 marks]