Questions and Answers of Physics Everyday Phenomena

A boat that can travel with a velocity of 12 m/s in still water is moving at maximum speed against the current of a stream that flows with a velocity of 5 m/s relative to the Earth. What is the
Does light traveling in empty space always travel in a straight line? Explain.
Would your experiences inside a freely falling elevator be similar in any way to those inside a spaceship moving with constant velocity when it is a long distance away from any planet or star?
When you are inside a closed space vehicle, is it possible for you to tell whether the vehicle is accelerating or whether you are simply near some massive body such as the sun or the Earth? Explain.
If an elevator is accelerating downward, will your apparent weight (as measured by a bathroom scale) be greater than your weight measured when the elevator is not accelerating? Explain.
If the velocity of an object is reduced to zero, does all of its energy disappear? Explain.
Is it completely correct to say that mass is converted into energy in a nuclear reaction such as a fission reaction? Explain.
Is the increase in kinetic energy of an object equal to the work done to accelerate the object for an object moving at a very high speed? Explain.
If we compress a spring and lock it into its newly compressed configuration, have we changed the mass of the spring? Explain.
Could we use the relativistic momentum expression p = γmv, for objects moving at small velocities? Explain.
Is Newton’s second law, written in the form Fnet = ma, valid for objects traveling at velocities near the velocity of light? Explain
Is it possible for an astronaut to leave on a space trip and to return a year before her twin sister was born? Explain.
Is it theoretically possible for a father to be younger (to have aged less) than his son or daughter? Explain.
A spaceship is moving with a large velocity past observer A, who is standing on Earth. Observer B is aboard the spaceship. Which of these observers measures the longer length for the length of the
A radioactive isotope with a certain half-life is moving with a high speed in a particle accelerator. Does an observer at rest in the lab measure the proper time for the half-life of this isotope?
A chess game taking place on Earth is seen by observer A, who is passing by in a spaceship. Observer B is standing on Earth looking over the shoulder of the players. Which of these two observers
Is it possible that two different observers will not agree on the time taken for a light beam to bounce off a mirror and return to its source? Explain.
Which of Einstein’s postulates deals most directly with the failure to detect motion of the Earth relative to the ether? Explain.
Do either of Einstein’s postulates contradict the classical assumptions of how relative velocities add? Explain.
Did the Michelson-Morley experiment succeed in measuring the velocity of the ether relative to the Earth? Explain.
What was the Michelson-Morley experiment designed to detect? Why did they expect that the speed of light might vary at different times of the year? Explain.
Was the ether (the assumed medium for light waves) presumed to exist in a vacuum? Explain.
Would it be appropriate, from the perspective of special relativity, to add the velocity of light relative to the Earth to the velocity of the Earth relative to the sun to obtain the velocity of
Does the addition of the velocities of things like airplanes and wind speed require use of the special theory of relativity? Explain.
If an airplane is flying in a crosswind blowing at an angle of 90° to the direction the airplane is pointed, will the speed of the plane relative to the ground be less than the speed of the plane
If a boat is moving across a stream, will the speed of the boat relative to the bank equal the numerical sum of speed of the boat relative to the water and the speed of the water relative to the
Is it possible that a person in a rowboat will not be able to move upstream? Explain.
If an airplane is flying in the same direction as the wind, will the velocity of the plane relative to the ground be greater than, less than, or equal to the velocity of the plane relative to the
If a boat is moving upstream, will the velocity of the boat relative to the bank of the stream be greater than the velocity of the boat relative to the water? Explain.
If a boat is moving downstream, will the velocity of the boat relative to the water be greater than the velocity of the boat relative to the stream bank? Explain.
Using the Rydberg formula, find the wavelength of the line in the Balmer series of the hydrogen spectrum for m = 3. (n = 2 for the Balmer series.)
Suppose that an X-ray beam has a wavelength of 5.0 x 10-9 m. What is the frequency of these X rays? (v = c = f λ)
How many electrons would be required to produce 5 microcoulombs (5 x 10-6 C) of negative charge? (e -1.6x 10-19 C)
If the mass of a hydrogen atom is 1.67x10-27 kg and the mass of an electron is 9.1 x 10-31 kg, how many electrons would be required to have a mass equivalent to one hydrogen atom?
If aluminum (Al), with an atomic weight of 27, combines with oxygen (O), with an atomic weight of 16, to form the compound aluminum oxide (Al2O3), how much oxygen would be required to react
If 38 g of fluorine (F) react completely with 2 g of hydrogen (H) to form the compound hydrogen fluoride (HF), what is the atomic weight of fluorine?
If carbon (C), with an atomic weight of 12, combines with oxygen (O), with an atomic weight of 16, to form carbon dioxide (CO2), how many grams of carbon would react with 96 g of oxygen?
If sodium (Na), with an atomic weight of 23, combines with oxygen (O), with an atomic weight of 16, to form the compound Na2O, what is the ratio of the mass of sodium to oxygen that you would expect
Why does the second row in the periodic table have more elements than the first row containing hydrogen and helium? Explain.
Does helium (He), with two electrons (one more than hydrogen), react chemically with other substances more readily or less readily than hydrogen? Explain.
The chemical properties of sodium (Na), with eleven electrons, are similar to those of lithium (Li), which has just three electrons. How do we explain this fact?
The Bohr model of the hydrogen atom predicts a circular orbit for the electron about the nucleus; the theory of quantum mechanics predicts a three-dimensional probability distribution for locating
According to the theory of quantum mechanics, is it possible to pinpoint exactly where an electron is located in an atom? Explain.
Does an electron have a wavelength? Explain.
What happens to the excess energy when the electron jumps from a higher-energy orbit to a lower-energy orbit in the hydrogen atom? Explain.
According to Bohr’s theory of the hydrogen atom, is it possible for the electron to orbit the nucleus with any possible energy? Explain.
According to Planck’s theory, can light be emitted from a blackbody radiator in continuously varying amounts of energy for a given wavelength or frequency? Explain.
Does the spectrum of hydrogen consist of randomly spaced wavelengths or is there a pattern to the spacing? Explain.
How are the atomic spectra of hydrogen or other gaseous elements generated experimentally? How are they measured? Explain.
Would you expect electrons to be effective in deflecting an alpha-particle beam? Explain.
What role did Rutherford’s scattering experiment play in our developing understanding of atomic structure? Explain.
Does most of the mass of the atom reside inside or outside of the nucleus? Explain.
When alpha particles are scattered from a thin piece of gold foil, why do most of them go through with very little deflection? Explain.
What are two important differences that distinguish alpha particles from beta particles when they are passed through a magnetic field? Explain.
Was it necessary for Becquerel’s phosphorescent materials to be exposed to sunlight for them to exhibit natural radioactivity? Explain.
Following Roentgen’s discovery of X rays, Becquerel discovered a seemingly similar type of radiation given off by phosphorescent materials containing uranium or thorium. Was this new radiation the
If the electron beam in a television tube is striking just one point on the screen at a time, how can we get a full picture? Explain.
Would you expect X rays to be produced by a television picture tube? Explain.
What characteristics of the negatively charged particles that make up cathode rays suggested to Thomson that they might be atomic building blocks? Explain.
Assuming that cathode rays are a beam of charged particles, how could you demonstrate that these particles are negatively charged? Explain.
Do X rays consist of electromagnetic waves? Explain.
Do cathode rays consist of electromagnetic waves? Explain.
Can the law of definite proportions be explained by a model in which different atoms of the same element have widely varying masses? Explain.
Is it possible for any number of hydrogen atoms to combine with just one atom of oxygen? Explain.
Does an atom of carbon (C) have the same mass as one atom of oxygen (O)? Explain.
In a chemical reaction, do the elements involved change into different elements as the reaction proceeds? Explain.
Is mass conserved in a chemical reaction? Explain.
When a substance is burned, are all of the products of that reaction solid substances that can be easily weighed? Explain.
Can the element iron (Fe) be changed to gold (Au) by heating it to a high enough temperature? Explain.
Is a chemical element the same as a chemical compound? Explain.
Two forces are applied to a merry-go-round with a radius of 1.2 m as shown in the diagram below. One force has a magnitude of 80 N and the other a magnitude of 50 N.a. What is the torque about the
A cue ball strikes a glancing blow against a second billiard ball initially at rest. Sketch the situation indicating the magnitudes and directions of the momentum vectors of each ball before and
A car and a small truck traveling at right angles to one another with the same speed collide and stick together. The truck’s mass is roughly twice the car’s mass. Sketch the direction of their
Two cars of equal mass collide at right angles to one another in an intersection. Their direction of motion after the collision is as shown in the diagram. Which car had the greater velocity before
Two lumps of clay, of equal mass, are traveling through the air at right angles to each other with velocities of equal magnitude. They collide and stick together. Is it possible that their velocity
Two lumps of clay traveling through the air in opposite directions collide and stick together. Their momentum vectors prior to the collision are shown in the diagram. Sketch the momentum vector of
A cue ball strikes an eight ball of equal mass, initially at rest. The cue ball stops and the eight ball moves forward with a velocity equal to the initial velocity of the cue ball. Is the collision
A ball bounces off a wall that is rigidly attached to the Earth. a. Is the momentum of the ball conserved in this process? Explain.b. Is the momentum of the entire system conserved? Explain,
A ball bounces off a wall with a velocity whose magnitude is less than it was before hitting the wall. Is the collision elastic? Explain.
If momentum is conserved in a collision, does this indicate conclusively that the collision is elastic? Explain.
Is the collision in question 24 elastic, partially inelastic, or perfectly inelastic? Explain.
A railroad car collides and couples with a second railroad car that is standing still. If external forces acting on the system are ignored, is the velocity of the system after the collision equal to,
A skateboarder jumps on a moving skateboard from the side. Does the skateboard slow down or speed up in this process? Explain, using conservation of momentum.
Suppose that on a perfectly still day, a sailboat enthusiast decides to bring along a powerful battery-operated fan in order to provide an air current for his sail, as shown in the diagram.a. What
Suppose an astronaut in outer space suddenly discovers that the tether connecting her to the space shuttle is cut and she is slowly drifting away from the shuttle. Assuming that she is wearing a tool
Suppose that you are standing on a surface that is so slick that you can get no traction at all in order to begin moving across this surface. Fortunately, you are carrying a bag of oranges. Explain
Is it possible for a rocket to function in empty space (in a vacuum) where there is nothing to push against except itself? Explain.
When a cannon rigidly mounted on a large boat is fired, is momentum conserved? Explain, being careful to clearly define the system being considered.
Two shotguns are identical in every respect (including the size of shell fired) except that one has twice the mass of the other. Which gun will tend to recoil with greater velocity when fired?
Two ice skaters, initially at rest, push off one another. What is the total momentum of the system after they push off? Explain.
A fullback collides midair and head-on with a lighter defensive back. If the two players move together following the collision, is it possible that the fullback will be carried backward? Explain.
A compact car and a large truck have a head-on collision. During the collision, which vehicle, if either, experiences: a. the greater force of impact? Explain.b. the greater impulse? Explain.c.
Which of Newton’s laws of motion are involved in justifying the principle of conservation of momentum? Explain.
Two objects collide under conditions where momentum is conserved. Is the momentum of each object conserved in the collision? Explain.
A ball is accelerated down a fixed inclined plane under the influence of the force of gravity. Is the momentum of the ball conserved in this process? Explain.
Is the principle of conservation of momentum always valid, or are there special conditions necessary for it to be valid? Explain.
A truck and a bicycle are moving side by side with the same velocity. Which, if either, will require the larger impulse to bring it to a halt? Explain.
If you catch a baseball or softball with your bare hand, will the force exerted on your hand by the ball be reduced if you pull your arm back during the catch? Explain.
The nearest star to our sun is about 4 light-years away a light-year is the distance that light travels in 1 year.a. How many seconds are there in a year?b. Since light travels at the rate of 3 x 108
The average distance from the sun to the Earth is approximately 1.5 x 108 km. How many seconds are required for light to travel from the sun to the Earth? (c = 3 x 108 m/s, 1 km = 1000 m)

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