Question

Beam AB has a negligible mass and thickness, and supports the 240-kg uniform block. It is pinned at A and rests on the top of a post, having a mass of 20 kg and negligible thickness. The coefficients of static friction at B and Care MB 0.4 and Mc = 0.2, respectively. (Figure 1) Part A Determine the minimum force P needed to move the post. Express your answer to three significant figures and include the appropriate units. ? p. Value Units Figure 1 of 1 Submit Request Answer < Return to Assignment Provide Feedback -1.5 m 1.5 m 1 m 0.75 m

Answer 1

SOL mu Given data :- Supports 240 kg uniform block mais cm) = 20 kg coefficient of friction at B CMB] = 0.4 Coefficient of friction at HW = 0.2 Line diagram of the given beam 240 kige A B P 1.5 m 15ml im 59 AL 1.5m F8 1.5 m 6m с NB E HA = 0 → Ng C3) - HC1-5) - 0 = NB (3) - (mg) ci-5)=0 → NB C3] - (240x 9.81) C1:5)= 0 C: : A = m2 .: NB = 1177.2 N NB -FB Mp im { Fy=0 Ne +P [3]-N8 -H = 0 Nete [2/2] - Ng-mg = Na + P (8]- #2 - 200 -81] = 0 c t 0 GP - 13H3-4 .: Na = 13+3-6-0-6P -70) 0.75m FC NC

.:. moment about "c" {Mc=0 FB C1.75) - P[%] +0.75) = 0 FB = 0.3428 P moment about "B" EMB=0 PC) - FCI-5) 0 —(2) .. (3) .:P: 2.1875 FC Therefore frictional force at “c" = HENc Fc > (4) .: &qc4) in &qc3) substituting -0.2 Nc ,'p = 2•1875 Co.2 NC] = 0.4375 Nc - (5) .: eq,ci) in &qc5) Substituling P = 0.4375 (1373.4 -0.6p) 600.8625 O• 2625 p .. 1.2625 p = 600.8625 475.93N :: p = Therefore minimum force “p' needed to move to post P = 475.93 N