can someone pls explain this problem? Thanks

Shamus uses two different methods to slide a rock of mass m, across the ground at a constant velocity. The coefcient of kinetic friction between the rock and the ground is pm. In method (a) he pushes on the rock with a force of magnitude F at a downward angle 8 as shown below. In method (b) he pulls on the rock using a rope with a force of magnitude F', at an upward angle 6, as shown below. The size of the angle 6 is the same for both methods. (I) Figure l: Pulling versus pushing. 15. The equation for F in terms of m, g, ,u and 9 is (you need to derive the equation), amg mug F : F : (a) sin 6 ,ucost? (b) sin3 -l- ,u cos 0 am umg F = d F = (c) cosQusin ( ) cos+usin9 16' The equation for F' in terms of m, g, ,u and 6' is (also derive), , _ umg , = #mg (a) F _ sinpcosf} (b) F sin6+pcos F\" = & F' = & (c) cos 9 p sine? (d) costiI + ,u sin 9 17. With regard to Fig. 1, which of the following is true? (a) Method (b) is easier because the normal force is less, which decreases the frictional force. (b) Method (at) is easier because the normal force is less, which decreases the frictional force. (c) Method 03) is easier because the normal force is greater. which decreases the frictional force. (d) Method (a) is easier because the normal force is greater, which decreases the frictional force. (e) The two methods are of equal difculty. 22