3. The 12-kg block shown rests on the smooth incline. If the spring is originally stretched 0.5 m, determine the total work done by all the forces acting on the block when a horizontal force P = 400 N pushes the block up the plane s = 2 m. s=2m Initial position of spring 2 sin 30⁰ m -k=30 N/m -2 cos 30° m- 400 N 30°

The homogeneous bar AB weighs 25 lb. Determine the magnitudes of the forces acting on the bar at A and B. Neglect friction.

Draw the FBD for the bar described in Prob. 5.1 if the bar is homogeneous of mass 50 kg. Count the unknowns.

2. Find the horizontal force P to start the motion of any part of the system of three blocks resting upon one another as shown. The weight of the blocks are W-300 KN, Ws= 100 KN and Wc =200 KN. Between A and B μ=0.30, between C and B, μ =0.20 and between C and the ground, p=0.10. 1 sni brod nog 02.0-4 B C 05.0-4 Solution: tamos quoy worla bre sosia asquar 005 300 en of jells400 N₁-300 F3 N-300- N₂=300 Assuming B and C will not move. F₁ = 300 (0.30) F₁ = 90 kN ne à bns A zelboß 1 P = 90 kN es ensla berb hebnu 02.0- y elin 05.0= q V in Celpris orllanimetsa MX 008 Assuming C will not move: al 1st F2=400 (0.20) = 80 kN OTE Bm ribirte F₂ vica Assuming the three blocks move: F3 = 0.10 (600) F3 = 60 kN P=60 KN Least force is 60 kN.