HW17-Solution

HW17-Solution - HW17 - Solutions Terry Cooke: Cal Poly San...

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Unformatted text preview: HW17 - Solutions Terry Cooke: Cal Poly San Luis Obispo Chapter 8, Solution 9 (a) To start block up the rail: s s 0.30 tan 1 0.30 16.70 Force triangle: P sin 51.70 500 N sin(180° 25 51.70 ) P 403 N (b) To prevent block from moving down: Force triangle: P sin 18.30 500 N sin(180° 25° 18.30°) P 229 N Chapter 8, Solution 11 (a) Free body: 20-kg block W1 F1 F 0: T (20 kg)(9.81 m/s 2 ) 196.2 N s N1 0.4(196.2 N) F1 78.48 N F1 0T 78.48 N Free body: 30-kg block W2 N2 F2 F 0: P P (30 kg)(9.81 m/s 2 ) 196.2 N 294.3 N s N2 294.3 N 490.5 N 0.4(490.5 N) 196.2 N T 0 353.2 N P 353 N F1 F2 78.48 N 196.2 N 78.48 N (b) Free body: Both blocks Blocks move together W F (50 kg)(9.81 m/s 2 ) 0 sN 490.5 N 0: P F P 0.4(490.5 N) 196.2 N P 196.2 N Chapter 8, Solution 15 FBD cabinet: Note: for tipping, NA FA 0 MB 0: (12 in.)W (32 in.)Ptip Ptip 0 2.66667 (a) All casters locked. Impending slip: FA FB sNA s NB Fy 0 : NA NA NB W NB W 0 W s 120 lb So FA FB Fx sW 0.3 0: P P FA FA FB FB 0 sW P (P 0.3W , Ptip 0 s NB 0.3(120 lb) or P 36.0 lb OK) (b) Casters at A free, so Impending slip: FA FB Fx 0: P FB 0 s NB P MA FB NB 0 P s 0 : (32 in.)P (12 in.)W (24 in.)N B 8 P 3W 6 P 0.3 0P 0.25W (P P 0.25W , Ptip 0.25(120 lb) OK) or P 30.0 lb PROBLEM 8.15 (Continued) (c) Casters at B free, so Impending slip: FB FA Fx 0 sNA 0: P FA 0P FA sNA NA MB 0 : (12 in.)W P s P 0.3 (32 in.)P (24 in.)N A 0 3W 8P 6 P 0.3 P 0 0.107143W 12.8572 ( P , Ptip OK) P 12.86 lb ...
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