Midterm2_Fall08_Key

# Midterm2_Fall08_Key - (l. = O 1. A 2 kg block is pushed 3...

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Unformatted text preview: (l. = O 1. A 2 kg block is pushed 3 in up a vertical wall with constant spged by a constant force of magnitude F applied at an angle 9 = 30° with the horizontal as shown in the ﬁgure below. If the coefﬁcient of kinetic friction between the block and the wall is 0.3, determine: (25 points) (a) The magnitude of the force F ( 7 points) (b) Normal force between the block and the wall (6 points) (0) Work done by the force F. (6 points) (d) Work done by the gravitational force. (6p01'nts) m e rcos.}1«-Fgmz;-~mg= 0 a F.— “’8 H 433???“ a v :- [C09 301% K Sln35] (D {23 N: ‘F. Sm go”: (amga-mgnzogﬁgﬂ (C) W: : E "3 Org“ 3‘31 ‘Jrlt‘og 306/3 : 33chi. 300 Mf— (’00 Wit—:8 . . . . b 2. The force actlng on an object IS given by F(x) 2 is — —2 , where a i 6 Nrn5 and b : 2 x x Nmz. (25 points) (a) Calculate the work done by this force in moving the object from X}: 1 m to xz = 5 m. (I 2 points) (b) Find an expression for the potential energy associated with this force and locate the positions at which a particle will be in equilibrium. (13 points) Y: K 5' timely {i _ g no M _ Lt- 7" .‘l ___g “e— _ \kr ax t+l>>< ._ qLD ij+2L§ I] (is) WF 2” AU F: ~5§Xhl Egg-“AX :gd :5 . Jr WWW” u H(¥\”~ '3: hisipijjfg :- q (“OASL‘A‘ Cr /- :O JFirf) 0% mgi- , b3 3 XS “02> Gt"- X :ng: X. X @1 I a: aliwm ' 3. A stone attached to the end of a non-elastic cord describes a vertical circular trajectory of 2 1n radius. When the stone is at its highest point, the tension in the cord TA=15 N, when the stone is at the lowest position of its trajectory, the tension TB=33 N. Calculate: (Use energetic considerations). (25 points) (\ ‘3 (a) Stone’s mass (9 points) (1)) Magnitude of the stone’s velocity in A (8 points) (0) Magnitude of the stone’s velocity in B (8 points) we“; (omkmxaxg C“ QMC‘i E19“ We 2 2 uv‘k’nomqg - * VQ’ ““ VQIQ- T+m 3m nth-g (1) P073“: lg+mg .44: m A a) (‘1:(23 m (fog-rgf :Tgkm (z) 3: 3 ._... .5 .3 "Elm: 03% I V3: %(T“+m€3) "5 ‘V’A: [qut‘l’mIS’ ‘(b) :- uoﬁw u u 6" 3/ 3: 1 03' H l 0%? \n/ 3 II T O“ 09 4. A block is released from rest at height h = 2.5 m and slides down a frictionless ramp onto a plateau, which has a length L : 9 m and Where the coefﬁcient of kinetic friction is 0.4. (25 points) (a) What is the block’s speed at the end of the incline plane (B)? (12 points) (b) Can the block reach the plateau’s end (C)? If the block cannot reach C, how far from B will it stop? (13 points) ESE) @3 {SE :0 :5 ){ﬁ*uh__\(g% h=2.5rn mgL‘n gm; --------- —- >< “""ﬂ =9m “Hz—{W ream tug Paka Sing-K r> l-Wélrlwmaa +2» ct.— MB .—_— mmmm ...
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## This note was uploaded on 07/30/2011 for the course PHY 2049 taught by Professor Saha during the Spring '08 term at University of Central Florida.

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Midterm2_Fall08_Key - (l. = O 1. A 2 kg block is pushed 3...

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