Question

5) [10 pts] Determine which adhesive design option is better Hardware stores often sell plastic hooks that can be mounted on walls with pressure-sensitive adhesive foam tape. Two designs are shown in (a) and (b) of the figure. Indicate which one you would buy when x = 3.4 in and y = 1.1 in. 0.75 The best design is Figure a OR Figure b

Answer 1

Solution: Caleuktion of Part 0. 4 3.4 Ya yout 14. aree Moment of inertea about Neutral aris Iné = (1, +4. Uwa-T.)*)+ + Lo + As Cher you] S By Paralled this thenone Area, A. (B.6 - 0.25% 0.25 = 0.1815 h Distance of centvid aris, 9 = 34 17 in. Area A Moment of inertia, (I) bd3 22 (0:) (315) 12 Part ② Area Aga 0.25x 1 = 0,25 in Distance of centroidal aris, Ý, B.He- 0.26 3.275 b. 12 0.715 in 4

Iga 12 AJ & Aa Ya c Area Moment of serta bu? 1x 0.2533 19 Is = 0.0013 hh Now, distance of Neutied anis from boltom, YNA (0.6875) (-1) + 0.25) (C..275) At Ag 0.7878+ 0.29) 'YNAE 2.0195 in Area Moment of inertia about Neutel aris (INA): Im = 1, +4-1) + 7 + A.Yo-Y) 0.7070 f2.87195-17) + 0.7157 0.0013+ 0.29(3.96-, 2.079812 I INA = 1.1870 inh P= alls a C G I distance of Plot of fire from Neutel areis YNA = 2.0195 y= 3.4²2.019521-3805 M Oo a) Benching Squation INA 9 Ma bending Moment = Pelilinch a 2.2.th.les .

; y = 1.3205 (ODAS 2. 447 teling 2.0795 in 4 c NA INA = 1.1810 in the 8.2 x 1.9205 1.8870 ODA - 2.644 ioline (bending stress at A) Care (6) :( Inverted) YNA -3.4-2.0995 = 1.3205 sh go Distance of fibre CA P2 als g=yNo=1.3205 in Blin M (GOA y Mx 1.3205 7 1. 1870 2.2×1,3205 2 hhth dolina TISTO Donclusions Stress at both cases at A is same. But case -A is safer than Bl because when we load, crack will start from in part B vas fast, Because stress womentation is more in case of them in section ® at point c. Therefore, CODA tr - (Omas I Case A is safer than case ß