1) A ladder with a mass of 15 kg and length 10.0 m leaned against a smooth wall. The height of the top ladder is 8.0 m from the rough floor. A painter who has a mass of 78 kg stands distance 1.6 m from the bottom of the ladder.
(a) Sketch a free body diagram showing all forces acting on the ladder. [3 marks] (b) Calculate the frictional force acts on the bottom of the ladder to keep it from slipping [6 marks]

2. A horizontal platform in the shape of a circular disk rotates freely in a horizontal plane about a frictionless vertical axle. The platform has a mass M= 100 kg and a radius R = 2.0 m. student whose mass is m = 60 kg walks slowly from the rim of the disk toward its centre. If the angular speed of the system is 2.0 rad s¹ when the student is at the rim, what is angular speed when he reaches a point r = 0.5 m from the centre? [4 marks]​