725.3 down N. Page 1 of N 200 N 100 N. 2m 3m 1 m 150 N

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Julianna Nichols
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1 Torque 4 (ANSWER KEY) Solve the ollowing roblems. A 650 N bo and a 490 N girl sit on a 50 N orch swing that is.7 m long. I the swing is suorted b a chain at each end, what is the tension in each chain when the bo sits 0.75 m rom one end and the girl 0.5 m rom the other? F=708N F=58N. A uniorm bridge, 0 m long and weighing 400,000 N, is suorted b two illars located m rom each end. I a 9,600 N car is arked 8 m rom one end o the bridge, how much orce does each illar exert? F=07000N F=600N. A uniorm.5 N meter stick is hung rom the ceiling b a single roe. A 500 g mass is hung at the 5 cm mark and a 650 g mass at the 70 cm mark. (a) What is the tension in the roe? (b) Where is the roe attached to the meter stick? T=.77N Hung at 50.4cm 4. An 850 N ainter stands. m rom one end o a m scaold suorted at each end b a steladder. The scaold weights 50 N and there is a 40 N aint can 0.5 m rom the end oosite the ainter. How much orce is exerted b each steladder? F=64 F= Use the igure at right (NOT DRAWN TO SCALE). (a) Calculate the torques exerted on the rod. (b) Find the magnitude and direction o the additional orce that must be exerted at the right end, erendicular to the rod, to maintain rotational equilibrium. 00 N 00 N 00 N m m m 75. down. 50 N 6. An exhausted gmnast hangs rom a bar b both arms in an eort to catch her breath. I her mass is 65 kg, what is the tension in each o her arms as she hangs in lace? 8.5 N Page o 6

2 7. At an art auction, John has acquired a ainting that now hangs rom a nail on his wall, as shown in the igure at right. I the ainting has a mass o.6 kg, what is the tension in each side o the wire suorting the ainting? Assume these two sides are equal lengths. 6.74/(x sinθ) 8. Michelle likes to swing on a tire tied to a tree branch in her ard. I Michelle and the tire have a combined mass o 8.5 kg, and Michelle is ulled back ar enough or her to make an angle o 0 with the vertical, what is the tension in the roe suorting Michelle and the tire? 0 9N 9. The cae-store owner wishes to hang a sign weighing 750 N so that cable A attached to the store makes a 0 angle with the horizontal. Cable B is attached to an adjoining building. Calculate the necessar tension in cables A and B. 500N to the let 00N to the right cable A cable B Joe s Cae Page o 6

3 0. A street lam weighs 50 N. It is suorted equall b wires that orm an angle o 0 with each other. a) What is the tension o each o these wires? b) I the angle between the wires is reduced to 90, what new orce does each wire exert? c) As the angle between the wires decrease, what haens to the orce in the wire? N in each 06.0N in each It reduces until the angle is zero and the orce is 75N in each. (Walker,. 45, #74) A 67.0-kg erson stands on a lightweight diving board suorted b two illars, one at the end o the board, the other.0-m awa. The illar at the end o the board exerts a downward orce o 88 N. (a) How ar rom that illar is the erson standing? (b) Find the orce exerted b the second illar. τ d F L d m g 0 d m g F.0 m 67.0 kg 9.8 m /s 88 N L 67.0 kg 9.8 m /s.49 m F F F 0 F F 67.0 kg 9.8 m /s 88 N 490 N.49 kn Page o 6

4 . (Walker,. 45, #75) A 47.0-kg uniorm rod 4.5 m long is attached to a wall with a hinge at one end. The rod is held in a horizontal osition b a wire attached to its other end. The wire makes an angle o 0.0 with the horizontal, and is bolted to the wall directl above the hinge. I the wire can withstand a maximum tension o 450 N beore breaking, how ar rom the wall can a 68.0-kg erson sit without breaking the wire? T r θ m g r m g L T sin L m g r m g 0 LT sin Lm g r r m g r 4.5 m 450 N sin m 47.0 kg 9.8 m /s 68.0 kg 9.8 m /s.5 m. (Walker,. 45, #78), Suose the ladder in the icture below is uniorm, 4.0 m long and weighs 60.0 N. Find the orces exerted on the ladder when the erson is (a) halwa u the ladder and (b) three-ourths o the wa u the ladder. Solution:. (a) Set 0 and solve or. Let b c because the erson is halwa u the ladder:. Determine the numerical value o : a b c m g 0 b cm g a c m g a 0.6 m 85 kg 9.8 m/s 60.0 N 46 N 0.5 kn.8 m Page 4 o 6

5 . Set F 0 and solve or x : F 0 x 4. Set F 0 and solve or 5. (b) Set 0 and solve or. Let 0.5 kn : F m g m g 0 m g m g 85 kg 9.8 m /s 60.0 N 894 N 0.89 kn b 4.0 m.8 m 0.94 m : 0.94 m 85 kg 9.8 m /s 0.6 m 60.0 N 4 4 bm g cm g a 6 N 0. kn 6. Let as in ste : 0. kn 7. The orce is unchanged: 894 N 0.89 kn.8 m 4. (Walker,. 45, #79) When ou arrive at Duke s Dude Ranch, ou are greeted b the large wooden sign shown in Figure 4. The let end o the sign is held in lace b a bolt, the right end is tied to a roe that makes an angle o 0.0 with the horizontal. I the sign is uniorm,.0 m long, and has a mass o 6.0 kg, what is (a) the tension in the roe, and (b) the horizontal and vertical comonents o the orce, F, exerted b the bolt? τ L T sin L m g kg 9.8 m /s T sin sin 0 9 N F T cos 0 x F x m g m g T cos cos sin tan F T sin kg 9.8 m /s tan N F T sin sin sin 6.0 kg 9.8 m/s 78.5 N Page 5 o 6

6 5. (Walker,., #) Based on the data in the icture below determine the m, m, and m that gives ou a well balance meal. m=0.7kg m=0.48kg m=0.99kg Page 6 o 6

AP Physics Multiple Choice Practice Torque

AP Physics Multiple Choice Practice Torque 1. A uniform meterstick of mass 0.20 kg is pivoted at the 40 cm mark. Where should one hang a mass of 0.50 kg to balance the stick? (A) 16 cm (B) 36 cm (C) 44