Physics for Scientists and Engineers with Modern Physics
4th Edition
ISBN: 9780131495081
Author: Douglas C. Giancoli
Publisher: Addison-Wesley
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Chapter 12, Problem 18P
(II) Three children are trying to balance on a seesaw, which includes a fulcrum rock acting as a pivot at the center, and a very light board 3.2 m long (Fig. 12–57). Two playmates are already on either end. Boy A has a mass of 45 kg, and boy B a mass of 35 kg. Where should girl C, whose mass is 25 kg, place herself so as to balance the seesaw?
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(II) Find the tension in the two cords shown in Fig. 9–52.
Neglect the mass of the cords, and assume that the angle 0 is
33° and the mass m is 190 kg.
FIGURE 9-52
m
Problem 12.
(II) A 75-kg adult sits at one end of a 9.0-m-long board.His 25-kg child sits on the other end. (a) Where should thepivot be placed so that the board is balanced, ignoringthe board’s mass? (b) Find the pivot point if the board isuniform and has a mass of 15 kg.
(II) A 20.0-m-long uniform beam weighing 650 N rests on
walls A and B, as shown in Fig. 9–62. (a) Find the maxi-
mum weight of a person who can walk to the extreme
end D without tipping the beam. Find the forces that the
walls A and B exert on the beam when the person is stand-
ing: (b) at D; (c) 2.0 m to the right of A.
- 20.0 m-
A
В
D
+3.0 m→
-12.0 m -
FIGURE 9-62 Problem 22.
Chapter 12 Solutions
Physics for Scientists and Engineers with Modern Physics
Ch. 12.1 - For simplicity, we wrote the equation in Example...Ch. 12.2 - We did not need to use the force equation to solve...Ch. 12.2 - CHAPTER-OPENING QUESTIONGuess Now! The diving...Ch. 12.2 - Why is it reasonable to ignore friction along the...Ch. 12.4 - Two steel wires have the same length and are under...Ch. 12 - Describe several situations in which an object is...Ch. 12 - A bungee jumper momentarily comes to rest at the...Ch. 12 - Prob. 3QCh. 12 - Your doctors scale has arms on which weights slide...Ch. 12 - A ground retaining wall is shown in Fig. 1240a....
Ch. 12 - Can the sum of the torques on an object be zero...Ch. 12 - A ladder, leaning against a wall, makes a 60 angle...Ch. 12 - A uniform meter stick supported at the 25-cm mark...Ch. 12 - Prob. 9QCh. 12 - Prob. 10QCh. 12 - Place yourself facing the edge of an open door....Ch. 12 - Prob. 12QCh. 12 - Prob. 13QCh. 12 - Which of the configurations of brick, (a) or (b)...Ch. 12 - Name the type of equilibrium for each position of...Ch. 12 - Is the Youngs modulus for a bungee cord smaller or...Ch. 12 - Examine how a pair of scissors or shears cuts...Ch. 12 - Materials such as ordinary concrete and stone are...Ch. 12 - (I) Three forces are applied to a tree sapling, as...Ch. 12 - (I) Approximately what magnitude force, FM, must...Ch. 12 - Prob. 3PCh. 12 - (I) A tower crane (Fig. 1248a) must always be...Ch. 12 - (II) Calculate the forces FA and FB that the...Ch. 12 - Prob. 6PCh. 12 - (II) The two trees in Fig. 1250 are 6.6 m apart. A...Ch. 12 - Prob. 8PCh. 12 - Prob. 9PCh. 12 - Prob. 10PCh. 12 - (II) Find the tension in the two cords shown in...Ch. 12 - (II) Find the tension in the two wires supporting...Ch. 12 - Prob. 13PCh. 12 - (II) The force required to pull the cork out of...Ch. 12 - (II) Calculate and FA and FB for the beam shown in...Ch. 12 - Prob. 16PCh. 12 - Prob. 17PCh. 12 - (II) Three children are trying to balance on a...Ch. 12 - (II) The Achilles tendon is attached to the rear...Ch. 12 - (II) A shop sign weighing 215 N is supported by a...Ch. 12 - (II) A traffic light hangs from a pole as shown in...Ch. 12 - (II) A uniform steel beam has a mass of 940 kg. On...Ch. 12 - (II) Two wires run from the top of a pole 2.6 m...Ch. 12 - (II) A large 62.0-kg board is propped at a 45...Ch. 12 - (II) Repeat Problem 24 assuming the coefficient of...Ch. 12 - (II) A 0.75-kg sheet hangs from a massless...Ch. 12 - (II) A uniform rod AB of length 5.0 m and mass M =...Ch. 12 - (III) A 56.0-kg person stands 2.0 m from the...Ch. 12 - (III) A door 2.30 m high and 1.30 m wide has a...Ch. 12 - (III) A cubic crate of side s = 2.0 m is...Ch. 12 - (III) A refrigerator is approximately a uniform...Ch. 12 - (III) A uniform ladder of mass m and length leans...Ch. 12 - Prob. 33PCh. 12 - (I) A nylon string on a tennis racket is under a...Ch. 12 - (I) A marble column of cross-sectional area 1.4 m2...Ch. 12 - (I) By how much is the column in Problem 35...Ch. 12 - (I) A sign (mass 1700 kg) hangs from the end of a...Ch. 12 - (II) How much pressure is needed to compress the...Ch. 12 - Prob. 39PCh. 12 - (II) At depths of 2000 m in the sea, the pressure...Ch. 12 - (III) A pole projects horizontally from the front...Ch. 12 - (I) The femur bone in the human leg has a minimum...Ch. 12 - (II) (a) What is the maximum tension possible in a...Ch. 12 - (II) If a compressive force of 3.3 104 N is...Ch. 12 - (II) (a) What is the minimum cross-sectional area...Ch. 12 - (II) Assume the supports of the uniform cantilever...Ch. 12 - (II) An iron bolt is used to connect two iron...Ch. 12 - (II) A steel cable is to support an elevator whose...Ch. 12 - (II) A heavy load Mg = 66.0 kN hangs at point E of...Ch. 12 - (II) Figure 1271 shows a simple truss that carries...Ch. 12 - (II) (a) What minimum cross-sectional area must...Ch. 12 - (II) onsider again Example 1211 but this time...Ch. 12 - (III) The truss shown in Fig. 1272 supports a...Ch. 12 - (III) Suppose in Example 1211, a 23-ton truck (m =...Ch. 12 - (III) For the Pratt truss shown in Fig. 1273,...Ch. 12 - (II) How high must a pointed arch be if it is to...Ch. 12 - The mobile in Fig. 1274 is in equilibrium. Object...Ch. 12 - A tightly stretched high wire is 36 m long. It...Ch. 12 - What minimum horizontal force F is needed to pull...Ch. 12 - A 28-kg round table is supported by three legs...Ch. 12 - When a wood shelf of mass 6.6 kg is fastened...Ch. 12 - Prob. 62GPCh. 12 - The center of gravity of a loaded truck depends on...Ch. 12 - In Fig. 1279, consider the right-hand...Ch. 12 - Assume that a single-span suspension bridge such...Ch. 12 - When a mass of 25 kg is hung from the middle of a...Ch. 12 - The forces acting on a 77,000-kg aircraft flying...Ch. 12 - A uniform flexible steel cable of weight mg is...Ch. 12 - A 20.0-m-long uniform beam weighing 650 N rests on...Ch. 12 - A cube of side l rests on a rough floor. It is...Ch. 12 - A 65.0-kg painter is on a uniform 25-kg scaffold...Ch. 12 - A man doing push-ups pauses in the position shown...Ch. 12 - A 23-kg sphere rests between two smooth planes as...Ch. 12 - A 15.0-kg ball is supported from the ceiling by...Ch. 12 - Parachutists whose chutes have failed to open have...Ch. 12 - A steel wire 2.3 mm in diameter stretches by...Ch. 12 - A 2500-kg trailer is attached to a stationary...Ch. 12 - Prob. 78GPCh. 12 - A 25-kg object is being lifted by pulling on the...Ch. 12 - A uniform 6.0-m-long ladder of mass 16.0 kg leans...Ch. 12 - There is a maximum height of a uniform vertical...Ch. 12 - A 95,000-kg train locomotive starts across a...Ch. 12 - A 23.0-kg backpack is suspended midway between two...Ch. 12 - A uniform beam of mass M and length l is mounted...Ch. 12 - Two identical, uniform beams are symmetrically set...Ch. 12 - If 35 kg is the maximum mass m that a person can...Ch. 12 - (a) Estimate the magnitude of the force FM the...Ch. 12 - One rod of the square frame shown in Fig. 1295...Ch. 12 - A steel rod of radius R = 15 cm and length 0,...Ch. 12 - A home mechanic wants to raise the 280-kg engine...Ch. 12 - A 2.0-m-high box with a 1.0-m-squarc base is moved...Ch. 12 - You are on a pirate ship and being forced to walk...Ch. 12 - A uniform sphere of weight mg and radius r0 is...Ch. 12 - Use the method of joints to determine the force in...Ch. 12 - A uniform ladder of mass m and length leans at an...Ch. 12 - In a mountain-climbing technique called the...Ch. 12 - (III) A metal cylinder has an original diameter of...Ch. 12 - (III) Two springs, attached by a rope, are...
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