Question

I came across a kinetics question and tried to solve it but I do not know know how to determine which direction the motion proceeds. I checked the solution and it does not show how the direction of the motion is decided. Just wondering how I can determine/ solve for which direction the motion proceeds before I even write the equations of motion. Here is the question:

13-37 The 10-kg block A rests on the 50-kg plate B in the position shown. Neglecting the mass of the rope and pulley, and using the coefficients of kinetic friction indicated, determine the time needed for block A to slide 0.5m on the plate when the system is released from rest 0.5 SOLUTION HAR- 02 Block A: +L Σ& -T + 0.2(84.96) + 10(9.81) sin30-104 T _ 66.04-_10⅔ mar. 30 Block B: N- 509.7 N -0.2(84-96)-0.1(509.7) _ T + 50(9.81 sin 30")-50Zg 1TI.28 T- 50a +/ Σ& _ mar. A+SB @a--@g Solving Eqs. (1)- (3): aB-1.854 m/s? a--1854m/sT 8458 In order to slide 05 m along the plate the block must move 0.25 m. Thus, 50 *3 AsA0.25 m -0.25 _ 0 + 0 + (-1.854)f2 Ans. t = 0.519s

In this problem it seems to be assumed that A moves up and B slides down. How can I solve for this? Thank you!

Answer 1

2 30° follow heto, ordinate System α。Mantioned. SfP Tor Mass A 3a CUS3 6 49550X9 61x coS30 50.7412N NA 2NA nMAO Sin | Distan

0n - SA Now