The mass of the bar is 4 kg. The coefficient of static friction between the bar and the floor is 0.3 Neglect frection between the bar and the wall. A) If a = 20°, what is the magnitude of the friction force exerted on the bar by the floor? B) What is the maximum angle a for which the bar will not slip?

Question 3(a) The non uniform XYZ bar which weighs 155 kg has its centre of gravity G at a distance 4 m from X. This bar rests on a homogeneous crate P. The static coefficient of friction between the bar and the crate is 0.31 while the same between the crate and the floor is 0.22. Determine the mass of the lightest crate P (in kilograms) that can be used to support this non uniform bar in the position shown in Figure 3. The height of the crate is 4.32 m and the length of the bar is 8.59 m. 4 m 3 m - 1 m - Figure 3 Question 3(b) Take an example from everyday life where you can identify the application of the concepts we learn in the "Dry friction" module. Sketch this example and discuss about the effect of friction on that particular scenario. Sketch does not have to be drawn to a scale. (Description should be 250 words or less).

A crate, which has a weight of W, is placed on an inclination. The force P is applied to prevent the crate from sliding down the inclination. a) Determine the minimum required force P, if the coefficient of static friction is u31. b) Determine the friction force (in magnitude) acting at the bottom of the crate if the force P=P1 and the coefficient of statie friction is µs1. c) Determine the minimum required force P, if the coefficient of static friction is u32. Use W=450 N, a=35°, us1=0.4, Hs2=0.75 and P=115 N. The minimum required force P in N is (if the coefficient of static friction is µs1) (round to the nearest integer): N The magnitude of friction in N is (if the force P-P, and the coefficient of static friction is u1) (round to the nearest integer): N The minimum required force P in N is (if the coefficient of static friction is µs2) (round to the nearest integer): N