At what altitude above Earth's surface would your weight be half of what it is at Earth's surface?
> When an object is in translational equilibrium, which of these statements is not true? (a) The vector sum of the forces acting on the object is zero. (b) The object must be stationary. (c) The object has a constant velocity. (d) The speed of the object i
> When a force is called a “normal” force, it is (a) the usual force expected given the arrangement of a system. (b) a force that is perpendicular to the surface of Earth at any given location. (c) a force that is always vertical. (d) a contact force perp
> In Conceptual Example 2.13, a horse pulls a sleigh at constant velocity. Suppose the horse wants to speed up. If it pulls forward on the sleigh with a larger force to try to make the net force on the sleigh nonzero, the sleigh will simultaneously pull ba
> Which of the fundamental forces binds quarks together to form protons, neutrons, and many exotic subatomic particles?
> Which of the fundamental forces has the shortest range?
> Which item in the following list is not a scalar? temperature, test score, stock value, humidity, velocity, mass.
> Which of the following forces bind electrons to nuclei to form atoms: strong force, contact force, electromagnetic force, gravitational force?
> Which of the following forces have an unlimited range: strong force, contact force, electromagnetic force, gravitational force?
> (a) Does a man weigh more at the North Pole or at the equator? (b) Does he weigh more at the top of Mt. Everest or at the base of the mountain?
> Which of the fundamental forces governs the motion of planets in the solar system? Is this the strongest or the weakest of the fundamental forces? Explain.
> The readings of the two spring scales shown in the drawing are the same. (a) Explain why they are the same. (b) What is the reading?
> Does the concept of a contact force apply to both a macroscopic scale and an atomic scale? Explain.
> A bird sits on a stretched clothesline, causing it to sag slightly. Is the tension in the line greatest where the bird sits, greater at either end of the line where it is attached to poles, or the same everywhere along the line? Treat the line as an idea
> For a problem about a crate sliding along an inclined plane, is it possible to choose the x-axis so that it is parallel to the incline?
> Pulleys and inclined planes are examples of simple machines. Explain what these machines do in Examples 2.4, 2.14, and (2.16) to make a task easier to perform.
> Compare the advantages and disadvantages of the two methods of vector addition (graphical and algebraic).
> If two vectors have the same magnitude, are they necessarily equal? If not, why not? Can two vectors with different magnitudes ever be equal?
> Which item/s in the following list is/are a vector quantity? volume, force, speed, length, time.
> You are standing on one end of a light wooden raft that has floated 3 m away from the pier. If the raft is 6 m long by 2.5 m wide and you are standing on the raft end nearest to the pier, can you propel the raft back toward the pier where a friend is sta
> You want to push a 65 kg box up a 25° ramp. The coefficient of kinetic friction between the ramp and the box is 0.30. With what magnitude force parallel to the ramp should you push on the box so that it moves up the ramp at a constant speed?
> An SUV collides with a Mini Cooper convertible. Is the force exerted on the Mini by the SUV greater than, equal to, or less than the force exerted on the SUV by the Mini? Explain.
> A heavy ball hangs from a string attached to a sturdy wooden frame. A second string is attached to a hook on the bottom of the lead ball. You pull slowly and steadily on the lower string. Which string do you think will break first? Explain.
> Can the x-component of a vector ever be greater than the magnitude of the vector? Explain.
> If a wagon starts at rest and pulls back on you with a force equal to the force you pull on it, as required by Newton's third law, how is it possible for you to make the wagon start to move? Explain.
> You want to lift a heavy box with a mass of 98.0 kg using the two ideal- pulley system as shown. With what minimum force do you have to pull down on the rope in order to lift the box at a constant velocity? One pulley is attached to the ceiling and one t
> A boy has stacked two blocks on the floor so that a 5.00 kg block is on top of a 2.00 kg block. (a) If the coefficient of static friction between the two blocks is 0.400 and the coefficient of static friction between the bottom block and the floor is 0.
> (a) If a spacecraft moves in a straight line between Earth and the Sun, at what point would the force of gravity on the spacecraft due to the Sun be as large as that due to Earth? (b) If the spacecraft is close to, but not at, this equilibrium point, do
> A student's head is bent over her physics book. The head weighs 50.0 N and is supported by the muscle force Fm exerted by the neck extensor muscles and by the contact force Fc exerted at the atlantooccipital joint. Given that the magnitude of Fm is 60.0
> A large wrecking ball of mass m is resting against a wall. It hangs from the end of a cable that is attached at its upper end to a crane that is just touching the wall. The cable makes an angle of θ with the wall. Ignoring friction between t
> Two canal workers pull a barge along the narrow waterway at a constant speed. One worker pulls with a force of 105 N at an angle of 28° with respect to the forward motion of the barge, and the other worker, on the opposite tow path, pulls at an angle of
> A tire swing hangs at a constant 12° angle to the vertical when a stiff breeze is blowing. In terms of the tire's weight W, (a) what is the magnitude of the horizontal force exerted on the tire by the wind? (b) What is the tension in the rope supporting
> By what percentage does the weight of an object change when it is moved from the equator at sea level, where the effective value of g is 9.784 N/kg, to the North Pole where g = 9.832 N/kg?
> The tallest spot on Earth is Mt. Everest, which is 8850 m above sea level. If the radius of Earth to sea level is 6370 km, how much does the gravitational field strength change between the sea level value at that location (9.826 N/kg) and the top of Mt.
> Spring scale A is attached to the ceiling. A 10.0 kg object is suspended from the scale. A second spring scale, B, is hanging from a hook at the bottom of the 10.0 kg object and a 4.0 kg object hangs from the second spring scale. (a) What are the readin
> A 50.0 kg crate is suspended between the floor and the ceiling using two spring scales, one attached to the ceiling and one to the floor. If the lower scale reads 120 N, what is the reading of the upper scale? Ignore the weights of the scales.
> What is the distinction between a vector and a scalar quantity? Give two examples of each.
> In the sport of curling, a player slides a 20.0 kg granite stone down a 38 m long ice rink. Draw FBDs for the stone (a) while it sits at rest on the ice; (b) while it slides down the rink; (c) during a head-on collision with an opponent's stone that was
> Four identical spring scales, A, B, C, and D are used to hang a 220.0 N sack of potatoes. (a) Assume that the scales have negligible weights and that all four scales show the same reading. What is the reading of each scale? (b) Suppose that each scale
> A box full of books rests on a wooden floor. The normal force the floor exerts on the box is 250 N. (a) You push horizontally on the box with a force of 120 N, but it refuses to budge. What can you say about the coefficient of static friction between the
> A book that weighs 10 N is at rest in six different situations. Blue arrows indicate forces exerted on the book by an object that is not shown. Rank the situations according to the magnitude of the normal force on the 10 N book due to the table, from sma
> A box sits on a horizontal wooden ramp. The coefficient of static friction between the box and the ramp is 0.30. You grab one end of the ramp and slowly lift it up, keeping the other end of the ramp on the ground. What is the angle between the ramp and t
> A binary star system consists of two stars of masses M1 and 4.0M1 a distance d apart. Is there any point where the net gravitational field due to the two stars is zero? If so, where is that point?
> Using the masses and mean distances found in Appendix B, calculate the net gravitational force on the Moon (a) during a lunar eclipse (Earth between Moon and Sun) and (b) during a solar eclipse (Moon between Earth and Sun).
> Find the ratio of Earth's gravitational force on a satellite when it is on the ground to the gravitational force exerted when the satellite is orbiting at an altitude of 320 km.
> (a) What is the magnitude of the gravitational force that Earth exerts on the Moon? (b) What is the magnitude of the gravitational force that the Moon exerts on Earth? See Appendix B for necessary information.
> An astronaut stands at a position on the Moon such that Earth is directly overhead and releases a Moon rock that was in her hand. (a) Which way will it fall? (b) What is the gravitational force exerted by the Moon on a 1.0 kg rock resting on the Moon's s
> How far above the surface of Earth does an object have to be in order for it to have the same weight as it would have on the surface of the Moon? (Ignore any effects from Earth's gravity for the object on the Moon's surface or from the Moon's gravity for
> During a balloon ascension, wearing an oxygen mask, you measure the weight of a 5.00 kg object and find that the value of the gravitational field strength at your location is 9.792 N/kg. How high above sea level, where the gravitational field strength wa
> The coefficient of static friction between a block and a horizontal floor is 0.40, while the coefficient of kinetic friction is 0.15. The mass of the block is 5.0 kg. A horizontal force is applied to the block and slowly increased. (a) What is the value
> Two cars are headed toward each other in opposite directions along a narrow country road. The cars collide head-on, crumpling up the hoods of both. Describe what happens to the car bodies in terms of the principle of inertia. Does the rear end of the car
> Find and compare the weight of a 65 kg man on Earth with the weight of the same man on (a) Mars, where g = 3.7 N/kg; (b) Venus, where g = 8.9 N/kg; and (c) Earth's Moon, where g = 1.6 N/kg.
> Find the altitudes above Earth's surface where Earth's gravitational field strength would be (a) two-thirds and (b) one-third of its value at the surface. Hint: First find the radius for each situation; then recall that the altitude is the distance from
> What is the approximate magnitude of the gravitational force exerted by the Sun on the Voyager 1 spacecraft when they are separated by 17 billion kilometers? The spacecraft has a mass of 722 kg.
> (a) Calculate your weight in newton’s. (b) What is the weight in newton of 250 g of cheese? (c) Name a common object whose weight is about 1 N.
> A woman who weighs 600 N sits on a chair with her feet on the floor and her arms resting on the chair's armrests. The chair weighs 100 N. Each armrest exerts an upward force of 25 N on her arms. The seat of the chair exerts an upward force of 500 N. (a)
> A hanging plant is suspended by a cord from a hook in the ceiling. Draw an FBD for each of these: (a) the system consisting of plant, soil, and pot; (b) the cord; (c) the hook; (d) the system consisting of plant, soil, pot, cord, and1hook. Label each for
> A skydiver, who weighs 650 N, is falling at a constant speed with his parachute open. Consider the apparatus that connects the parachute to the skydiver to be part of the parachute. The parachute pulls upward on the skydiver with a force of 620 N. Consid
> A skydiver, who weighs 650 N, is falling at a constant speed with his parachute open. Consider the apparatus that connects the parachute to the skydiver to be part of the parachute. The parachute pulls upward on the skydiver with a force of 620 N. (a) Id
> A toy freight train consists of an engine and three identical cars. The train is moving to the right at constant speed along a straight, level track. Three spring scales are used to connect the cars as follows: spring scale A is located between the engin
> Tamar wants to cut down a dead poplar tree with her chain saw, but she does not want it to fall onto the nearby gazebo. Yoojin, a physicist, suggests they tie a rope taut from the poplar to an oak tree and then pull sideways on the rope as shown in the f
> While trying to decide where to hang a framed picture, you press it against the wall to keep it from falling. The picture weighs 5.0 N, and you press against the flat frame with a force of 6.0 N at an angle of 40° from the vertical. (a) What
> The coefficient of static friction between block A and a horizontal floor is 0.45, and the coefficient of static friction between block B and the floor is 0.30. The mass of each block is 2.0 kg, and they are connected together by a cord. (a) If a horizo
> When you hold up a 50 N object in your hand, with your forearm horizontal and your palm up, the upward force exerted by your biceps is much larger than 50 N—perhaps as much as 5000 N. How can that be? What other forces are acting on you
> You grab a book and give it a quick push across the top of a horizontal table. After a short push, the book slides across the table, and because of friction, comes to a stop. (a) Draw an FBD of the book while you are pushing it. (b) Draw an FBD of the
> You want to hang a 15 N picture as in the figure (a) using some very fine twine that will break with more than 12 N of tension. Can you do this? What if you have it as illustrated in Figure (b)?
> A box containing a new TV weighs 350 N. Phineas is pushing horizontally on it with a force of 150 N, but it doesn't budge. (a) Identify all the forces acting on the crate. Describe each as: (type of force) exerted on the crate by (object). (b) Identify
> A bike is hanging from a hook in a garage. Consider the following forces: (1) the force of Earth pulling down on the bike, (2) the force of the bike pulling up on Earth, and (3) the force of the hook pulling up on the bike. (a) Which two forces are equa
> A freight train consists of an engine and several identical cars on level ground. Determine whether each of these statements is correct or incorrect and explain why. (a) If the train is moving at constant speed, the engine must be pulling with a force g
> An ideal pulley is hung from the ceiling by a rope. A block of mass M is suspended by another rope that passes over the pulley and is attached to the wall. The rope fastened to the wall makes a right angle with the wall. Ignore the masses of the rope and
> A 45 N lithograph is supported by two wires. One wire makes a 25° angle with the vertical and the other makes a 15° angle with the vertical. Find the tension in each wire.
> A 2.0 kg ball tied to a string fixed to the ceiling is pulled to one side by a force F. Just before the ball is released and allowed to swing back and forth, (a) how large is the force F that is holding the ball in position and (b) what is the tension in
> A crow perches on a clothesline midway between two poles. Each end of the rope makes an angle of θ below the horizontal where it connects to the pole. If the weight of the crow is W, what is the tension in the rope? Ignore the weight of the
> The drawing shows a wire attached to two back teeth and stretched across a front tooth. The purpose of this arrangement is to apply a force F to the front tooth. (The figure has been simplified by drawing the wire as if it ran straight from the front too
> A 200.0 N sign is suspended from a horizontal strut of negligible weight. The force exerted on the strut by the wall is horizontal. Draw an FBD to show the forces acting on the strut. Find the tension T in the diagonal cable supporting the strut.
> Two boxes with different masses are tied together on a frictionless ramp surface. What is the tension in each of the cords?
> Two springs are connected in series so that spring scale A hangs from a hook on the ceiling and a second spring scale, B, hangs from the hook at the bottom of scale A. Apples weighing 120 N hang from the hook at the bottom of scale B. What are the readin
> A spring scale hangs from a cord that is attached to a hook in the ceiling. A 10 kg object hangs from a second cord connected to the bottom of the scale. The weights of the cords and the scale are negligible. (a) What is the reading of the scale? (b) T
> You are pulling a suitcase through the airport at a constant speed by exerting a force of 25.0 N at angle 30.0° from the vertical. What is the force of friction acting on the suitcase?
> (a) What assumptions do you make when you call the reading of a bathroom scale your “weight”? What does the scale really tell you? (b) Under what circumstances might the reading of the scale not be equal to your weight?
> An 85 kg skier is sliding down a ski slope at a constant velocity. The slope makes an angle of 11° above the horizontal direction. Ignore air resistance. (a) What is the force of kinetic friction acting on the skier? (b) What is the coefficient of kineti
> An 80.0 N crate of apples sits at rest on a ramp that runs from the ground to the bed of a truck. The ramp is inclined at 20.0° to the ground. (a) What is the normal force exerted on the crate by the ramp? (b) The interaction partner of this normal for
> Mechanical advantage is the ratio of the force required without the use of a simple machine to that needed when using the simple machine. Compare the force to lift an object with that needed to slide the same object up a frictionless incline and show tha
> (a) In Example 2.14, if the movers stop pushing on the safe, can static friction hold the safe in place without having it slide back down? (b) If not, what minimum force needs to be applied to hold the safe in place?
> Before hanging new William Morris wallpaper in her bedroom, Brenda sanded the walls lightly to smooth out some irregularities on the surface. The sanding block weighs 2.0 N and Brenda pushes on it with a force of 3.0 N at an angle of 30.0° with respect t
> A crate of artichokes is on a ramp that is inclined 10.0° above the horizontal. Give the direction of the normal force and the friction force acting on the crate in each of these situations. (a) The crate is at rest. (b) The crate is sliding up the ramp.
> A crate of potatoes of mass 18.0 kg is on a ramp with angle of incline 30° to the horizontal. The coefficients of friction are μs = 0.75 and μk = 0.40. Find the normal force (magnitude) and the frictional force (magnitude and direction) on the crate if t
> A crate of potatoes of mass 18.0 kg is on a ramp with angle of incline 30° to the horizontal. The coefficients of friction are μs = 0.75 and μk = 0.40. Find the normal force (magnitude) and the frictional force (magnitude and direction) on the crate if t
> A crate of potatoes of mass 18.0 kg is on a ramp with angle of incline 30° to the horizontal. The coefficients of friction are μs = 0.75 and μk = 0.40. Find the normal force (magnitude) and the frictional force (magnitude and direction) on the crate if t
> A crate of potatoes of mass 18.0 kg is on a ramp with angle of incline 30° to the horizontal. The coefficients of friction are μs = 0.75 and μk = 0.40. Find the normal force (magnitude) and the frictional force (magnitude and direction) on the crate if t
> (a) Is it possible for the sum of two vectors to be smaller in magnitude than the magnitude of either vector? (b) Is it possible for the magnitude of the sum of two vectors to be larger than the sum of the magnitudes of the vectors?
> A person is standing on a bathroom scale. Which of the following is not a force exerted on the scale: a contact force due to the floor, a contact force due to the person's feet, the weight of the person, the weight of the scale?
> When sodium is bombarded with electrons accelerated through a potential difference ΔV, its x - ray spectrum contains emission peaks at 1.04 keV and 1.07 keV. Find the minimum value of ΔV required to produce both of these peaks.
> What minimum accelerating voltage is required to produce an x - ray with a wavelength of 70.0 pm?
> Calculate the minimum - wavelength x - ray that can be produced when a target is struck by an electron that has been accelerated through a potential difference of (a) 15.0 kV and (b) 1.00 x 102 kV. (c) What happens to the minimum wavelength as the potent
> The extremes of the x - ray portion of the electromagnetic spectrum range from approximately 1.0 x 10-8 m to 1.0 x 10-13 m. Find the minimum accelerating voltages required to produce wavelengths at these two extremes.
> Two light sources are used in a photoelectric experiment to determine the work function for a particular metal surface. When green light from a mercury lamp (λ = 546.1 nm) is used, a stopping potential of 0.376 V reduces the photocurrent to zero. (a) Bas
> When monochromatic light of an unknown wavelength falls on a sample of silver, a minimum potential of 2.50 V is required to stop all of the ejected photoelectrons. Determine the (a) Maximum kinetic energy and (b) Maximum speed of the ejected photoelectro
> Lithium, beryllium, and mercury have work functions of 2.30 eV, 3.90 eV, and 4.50 eV, respectively. Light with a wavelength of 4.00 x 102 nm is incident on each of these metals. (a) Which of these metals emit photoelectrons in response to the light? Why?
> The work function for platinum is 6.35 eV. (a) Convert the value of the work function from electron volts to joules. (b) Find the cutoff frequency for platinum. (c) What maximum wavelength of light incident on platinum releases photoelectrons from the pl
> The work function for zinc is 4.31 eV. (a) Find the cutoff wavelength for zinc. (b) What is the lowest frequency of light incident on zinc that releases photoelectrons from its surface? (c) If photons of energy 5.50 eV are incident on zinc, what is the m
