Explanation Consider that if A → = A x i ^ + A y j ^ + A z k ^ then − A → = ( − A x ) i ^ + ( − A y ) j ^ + ( − A z ) k ^ , if B → = B x i ^ + B y j ^ + B z k ^ then − B → = ( − B x ) i ^ + ( − B y ) j ^ + ( − B z ) k ^ Conclusion: In order show that A → ⋅ ( − B → ) = − A → ⋅ B → Substitute A x i ^ + A y j ^ + A z k ^ for A → , ( − A x ) i ^ + ( − A y ) j ^ + ( − A z ) k ^ for − A → , B x i ^ + B y j ^ + B z k

Physics for Scientists and Engineers with Modern Physics

4th Edition

ISBN: 9780131495081

Author: Douglas C. Giancoli

Publisher: Addison-Wesley

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Chapter 7, Problem 19P

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Show that A→⋅(−B→)=−A→⋅B→.

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Chapter 7, Problem 18P

Chapter 7, Problem 20P

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Chapter 7 Solutions

Physics for Scientists and Engineers with Modern Physics

Ch. 7.1 - A box is dragged a distance d across a floor by a...Ch. 7.1 - Return to the Chapter-Opening Question, page 163,...Ch. 7.4 - (a) Make a guess: will the work needed to...Ch. 7.4 - Can kinetic energy ever be negative?Ch. 7.4 - Prob. 1EE Ch. 7 - In what ways is the word work as used in everyday...Ch. 7 - A woman swimming upstream is not moving with...Ch. 7 - Can a centripetal force ever do work on an object?...Ch. 7 - Why is it tiring to push hard against a solid wall...Ch. 7 - Does the scalar product of two vectors depend on...

Ch. 7 - Can a dot product ever he negative? If yes, under...Ch. 7 - Prob. 7Q Ch. 7 - Does the dot product of two vectors have direction...Ch. 7 - Can the normal force on an object ever do work?...Ch. 7 - You have two springs that are identical except...Ch. 7 - Prob. 11Q Ch. 7 - In Example 710, it was stated that the block...Ch. 7 - Two bullets are fired at the same time with the...Ch. 7 - Does the net work done on a particle depend on the...Ch. 7 - A hand exerts a constant horizontal force on a...Ch. 7 - (I) How much work is done by the gravitational...Ch. 7 - (I) How high will a 1.85-kg rock go if thrown...Ch. 7 - (I) A 75.0-kg firefighter climbs a flight of...Ch. 7 - (I) A hammerhead with a mass of 2.0 kg is allowed...Ch. 7 - (II) Estimate the work you do to mow a lawn 10 m...Ch. 7 - (II) A lever such as that shown in Fig. 720 can be...Ch. 7 - (II) What is the minimum work needed to push a...Ch. 7 - (II) Eight books, each 4.0cm thick with mass 1.8...Ch. 7 - (II) A box of mass 6.0 kg is accelerated from rest...Ch. 7 - (II) (a) What magnitude force is required to give...Ch. 7 - (II) A 380-kg piano slides 3.9m down a 27 incline...Ch. 7 - (II) A gondola can carry 20 skiers, with a total...Ch. 7 - (II) A 17,000-kg jet takes off from an aircraft...Ch. 7 - (II) A 2200-N crate rests on the floor. How much...Ch. 7 - (II) A grocery cart with mass of 16 kg is being...Ch. 7 - (I) What is the dot product of...Ch. 7 - (I) For any vector V=Vxi+Vyj+Vzk show that...Ch. 7 - (I) Calculate the angle between the vectors:...Ch. 7 - Prob. 19P Ch. 7 - (I) Vector V1 points along the z axis and has...Ch. 7 - (II) Given the vector A=3.0i+1.5j, find a vector...Ch. 7 - (II) A constant force F=(2.0i+4.0j)N acts on an...Ch. 7 - (II) If A=9.0i8.5j,B=8.0i+7.1j+4.2k,and...Ch. 7 - (II) Prove that AB=AxBx+AyBy+AzBz, starting from...Ch. 7 - (II) Given vectors A=4.8i+6.8jandB=9.6i+6.7j,...Ch. 7 - (II) Show that if two nonparallel vectors have the...Ch. 7 - (II) Let V=20.0i+22.0j14.0k. What angles does this...Ch. 7 - (II) Use the scalar product to prove the law of...Ch. 7 - (II) Vectors A and B are in the xy plane and their...Ch. 7 - (II) A and B are two vectors in the xy plane that...Ch. 7 - (II) Suppose A=1.0i+1.0j2.0k and B=1.0i+1.0j+2.0k,...Ch. 7 - (II) Find a vector of unit length in the xy plane...Ch. 7 - (III) Show that the scalar product of two vectors...Ch. 7 - (I) In pedaling a bicycle uphill, a cyclist exerts...Ch. 7 - (II) A spring has k = 65N/m. Draw a graph like...Ch. 7 - (II) If the hill in Example 72 (Fig. 74) was not...Ch. 7 - (II) The net force exerted on a particle acts in...Ch. 7 - (II) If it requires 5.0 J of work to stretch a...Ch. 7 - (II) In Fig. 79 assume the distance axis is the x...Ch. 7 - (II) The force on a particle, acting along the x...Ch. 7 - (II) A child is pulling a wagon down the sidewalk....Ch. 7 - (II) The resistance of a packing material to a...Ch. 7 - (II) The force needed to hold a particular spring...Ch. 7 - (II) At the top of a pole vault, and athlete...Ch. 7 - (II) Consider a force F1=A/xwhich acts on an...Ch. 7 - (II) Assume that a force acting on an object is...Ch. 7 - (II) An object, moving along the circumference of...Ch. 7 - (III) A 2800-kg space vehicle, initially at rest,...Ch. 7 - (III) A 3.0-m-long steel chain is stretched out...Ch. 7 - (I) At room temperature, an oxygen molecule, with...Ch. 7 - (I) (a) If the kinetic energy of a particle is...Ch. 7 - (I) How much work is required to stop an electron...Ch. 7 - (I) How much work must be done to stop a 1300-kg...Ch. 7 - (II) Spiderman uses his spider webs to save a...Ch. 7 - (II) A baseball (m=145g) traveling 32mA moves a...Ch. 7 - (II) An 85-g arrow is fired from a bow whose...Ch. 7 - (II) A mass m is attached to a spring which is...Ch. 7 - (II) If the speed of a car is increased by 50%, by...Ch. 7 - (II) A 1200-kg car rolling on a horizontal surface...Ch. 7 - (II) One car has twice the mass of a second car,...Ch. 7 - (II) A 4.5-kg object moving in two dimensions...Ch. 7 - (II) A 265-kg load is lifted 23.0m vertically with...Ch. 7 - (II) (a) How much work is done by the horizontal...Ch. 7 - (II) (a) How much work is done by the horizontal...Ch. 7 - (II) At an accident scene on a level road,...Ch. 7 - (II) A 46.0-kg crate, starting from rest, is...Ch. 7 - (II) A train is moving along a track with constant...Ch. 7 - (III) We usually neglect the mass of a spring if...Ch. 7 - (III) An elevator cable breaks when a 925-kg...Ch. 7 - (a) A 3.0-g locust reaches a speed of 3.0m/s...Ch. 7 - In a certain library the first shelf is 12.0 cm...Ch. 7 - A 75-kg meteorite buries itself 5.0 m into soft...Ch. 7 - A 6.10-kg block is pushed 9.25 m up a smooth 37.0...Ch. 7 - Prob. 74GP Ch. 7 - Two forces, F1=(1.50i0.80j+0.70k)Nand...Ch. 7 - The barrels of the 16-in, guns (bore diameter = 16...Ch. 7 - A varying force is given by F = Aekx, where x is...Ch. 7 - The force required to compress an imperfect...Ch. 7 - A force F=(10.0i+9.0j+12.0k)kNacts on a small...Ch. 7 - In the game of paintball, players use guns powered...Ch. 7 - A softball having a mass of 0.25 kg is pitched...Ch. 7 - An airplane pilot fell 370 m after jumping from an...Ch. 7 - Many cars have 5 mi/h (8 km/h) bumpers that are...Ch. 7 - What should be the spring constant k of a spring...Ch. 7 - Assume a cyclist of weight mg can exert a force on...Ch. 7 - A simple pendulum consists of a small object of...Ch. 7 - A car passenger buckles himself in with a seat...Ch. 7 - As an object moves along the x axis from x = 0.0 m...Ch. 7 - A cyclist starts from rest and coasts down a 4.0...Ch. 7 - Stretchable ropes ate used to safely arrest the...Ch. 7 - A small mass m hangs at rest from a vertical rope...Ch. 7 - (II) The net force along the linear path of a...Ch. 7 - (II) When different masses are suspended from a...

Knowledge Booster

Show that A → ⋅ ( − B → ) = − A → ⋅ B → .

Solution Summary: The author illustrates how the dot product of two vectors stackrelto (A) and left (B) is shown.

Show that A→⋅(−B→)=−A→⋅B→.

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Chapter 7 Solutions