PHY 102: Exam and Homework Q's

The centripetal force that keeps Earth in orbit around the Sun is a tension force.

False

The synodic period and sidereal period of the Moon are the same length of time.

False

Newton's Universal Law of Gravitation states that...

D. the farther apart two objects are, the weaker the force of gravity is between them

Our Milky Way galaxy is classified as an elliptical galaxy.

False

Which of the following has the least amount of momentum? (Use p=mv, where p is momentum, m is mass, and v is velocity).

A. a 16 kg mass moving at 10 m/s

A sled is sliding down a snowy hill at a constant speed, when it hits a patch of ice. While on the ice, the sled begins to accelerate in its slide down the hill. What can we say about the coefficient of kinetic friction of the snow and ice?

A. the kinetic friction of the ice is less than the kinetic friction of the snow

The magnetic force on a charged particle... (Check all that apply)

A. ...can cause the charged particle to change its direction of motion. F. ...is zero unless the charged particle is in motion.

Nuclear fusion uses up the hydrogen (chemical symbol H) in a main sequence star's core by...

A. ...combining 4 H nuclei to form 1 helium, and in the process, converting some of the mass into a large amount of energy.

The color which a star appears is most directly related to...

A. ...its surface temperature.

Which of the following would be a source of discrete spectral lines (an emission line spectrum)? (Check all that apply).

A. A sodium vapor lamp (like those yellowish street lights). D. A hydrogen gas tube carrying an electric current.

What happens to the kinetic energy in a TOTALLY elastic collision?

A. Kinetic energy is conserved (it is all recovered and measured as kinetic energy of the objects after the collision).

A human "cannonball" is shot from a cannon and follows a parabolic path into a net. At the top of her trajectory...

A. None of the other answers are correct (all different types of energy)

Of the cosmological models listed below, which placed the Earth at the center of the model? (Check all that apply)

A. Ptolemaic (Claudius Ptolomy) B. Aristotelian (Aristotle) D. Tychonic (Tycho Brahe)

What are some of the major differences between the terrestrial (inner) planets and the Jovian (outer) planets in our Solar System? (Check all that apply).

A. Terrestrial planets have higher densities than the Jovian planets. B. Terrestrial planets have weaker magnetic fields than the Jovian planets. C. Terrestrial planets have much less complicated satellite and ring systems than the Jovian planets. D. Terrestrial planets have less substantial atmospheres than the Jovian planets. E. Terrestrial planets are closer to the Sun and therefore warmer than the Jovian planets. F. Terrestrial planets have slower rotation rates than the Jovian planets. G. Terrestrial planets are less massive and smaller than the Jovian planets. H. Terrestrial planets have rocky surfaces while the Jovian planets have gaseous surfaces.

Which of the following explanations correctly describes the reason Earth experiences seasons?

A. The Earth's Northern hemisphere is tilted 23.5 degrees toward the Sun in Summer and away from the Sun in Winter

Which of the following are true comparisons between the electric force (described by Coulomb's Law) and the gravitational force (described by Newton's Universal Law of Gravitation)? Check all that apply.

A. There are two kinds of charge that are subject to the electric force, but only one kind of mass subject to the gravitational force. C. Gravity only attracts, while the electric force either attracts or repels. E. Gravity depends on the amount of mass involved, while the electric force depends on the amount of charge. F. Gravity is much weaker than the electric force.

Color, Wavelength, Frequency, and Energy are all equivalent descriptions for a particular type of light wave.

A. True

Two ingerdients in the scientific method are careful observations, and the formulation of a model (or theory) which adequately explains the observations. The history of astronomy in the post-renaissance period provides a beautiful example of this in the cooperation between...

A. Tycho Brahe's observations, and Johannes Kepler's model

The two keys which led to the correct modern picture of our solar system were...

A. a heliocentric model with elliptical orbits of the planets

The lowest frequency ranges of light waves (radio waves and microwaves)...

A. are low energy, and therefore relatively safe for human exposure

Which of the following are parts of the scientific process, as described in class? (Check all that apply).

A. building a theory or hypothesis E. careful observation or measurement F. experimental tests of a hypothesis H. modification of the model or theory (if needed)

the Law of Conservation of Energy states that energy...

A. cannot be created B. cannot be destroyed C. may be changed from one form into another D. stays constant within a closed system

An object will possess gravitational potential energy (GPE) because of...

A. its height above the ground

Venus is the nearest planet in our solar system to the Earth, and is a more massive object than our Moon. If Venus is about 99 times further away from Earth than the Moon, and about 66 times the mass of the Moon, how does Venus's gravitational force on the Earth compare to the Moon's gravitational force on the Earth? (You can use Newton's Universal Law of Gravitation: F = GmM/r2, and if you express the two forces as a ratio, you shouldn't require any additional information or constants to answer the question).

B. 0.0067 times the strength of the Moon's gravitational force

While driving from Bloomington/Normal to Chicago, A person drives the first 50 km at a velocity of 100 km/hr, then stops for half an hour, then drives the remaining 150 km at a velocity of 90 km/hr. What is the average velocity for the total trip?

B. 75 km/hr

One way to produce a magnetic field, is with...

B. ...an electric current.

Sending an electric current through a gas sealed in a transparent glass tube will result in...

B. ...spectral lines at wavelengths characteristic of the gas (an emission spectrum).

Based upon the information in an H-R diagram...

B. ...the cooler main sequence stars would have a lower luminosity.

What is one reason the Moon's surface is almost entirely covered with craters, while the Earth's surface is not?

B. The Earth's atmosphere protects the surface from meteors. They burn up before they reach the ground.

Which of the following explanations correctly describes the reason Earth's Moon shows phases?

B. The changing angle between the Sun, Moon, and Earth causes a variable fraction of the Moon's surface to reflect sunlight

Velocity is described as a change in position. In a similar way, acceleration can best be described as...

B. a change in velocity

You're driving down the highway and a bug hits your windshield and sticks there. Which undergoes the greater change in momentum?

B. both undergo the same sized change in momentum

The Sun (and our solar system) is located where in our galaxy?

B. in the disk, about 28,000 light years (2/3 of the way out) from the center

The celestial sphere...

B. is an imaginary sphere around the Earth with the stars all fixed upon it D. is a coordinate system for the sky, similar to latitude and longitude

A Moon phase that is "gibbous" means that...

B. more than half the Moon is lit up by sunlight

The flow rate of electric charge is measured in units called Amperes (or amps, for short). What is the equivalent metric measure of one ampere of electric current?

B. one Coulomb/second

A "centripetal" force will act on an object in a direction...

B. that is toward the center of the circle the object is moving

A collision between a large truck initially at rest, and a small moving car causes the two vehicles to stick together after the crash. Which of the following statements is true about the motion of the combined wreck after the collision?

B. the combined objects move together with a speed less than the original speed of the small car

Which of the following definitions correctly describe the ecliptic? (Check all that apply)

B. the plane in which the Earth orbits the Sun D. the apparent path of the Sun relative to the background stars E. the apparent path of the Sun on the celestial sphere

A firecracker initially at rest explodes into two pieces. One piece flies to the left with a velocity, v. The other piece flies in exactly the opposite direction (to the right) and has one third the mass of the first piece. Using conservation of momentum, what will be the velocity of the second piece in terms of v?

C. 3 times v

In general, Newton's Second Law (F = ma) represents a relationship between...

C. a combination of many forces, many masses, and many accelerations

Galileo's experiments with falling motion (due to gravity), used inclined planes to observe objects as they rolled down a slope. From these experiments, he determined that if you ignore air resistance...

C. free fall motion is the same for all objects and equal to 9.8 m/s2

The main nuclear reaction which powers the Sun is...

C. ...fusion of hydrogen into helium.

Which of the following statements is correct for eclipses in the Sun-Earth-Moon system?

C. A total lunar eclipse occurs only at full Moon

The Ptolemaic cosmology (Claudius Ptolomy's model of the solar system) was predominantly believed for many centuries in Europe. Which statement below is FALSE about the Ptolemaic system?

C. It was much simpler than the earlier models and therefore not as accurate.

What happens to the kinetic energy in a totally IN-elastic collision?

C. Kinetic energy is completely converted into other forms of energy and none remains after the collision (there is no motion of any of the objects after the collision).

A light year is...

C. a unit of distance

When galaxies interact with one another, which of the following observations is NOT something we might see happening?

C. all the stars in the galaxies may die out simultaneously

Which of the following are a consequence of the Earth's yearly motion around the Sun? (Check all that apply)

C. different stars are seen at night at different times of the year D. the Sun appears in different constellations in different months E. the Sun changes its height in the sky in different seasons

Suppose you look up in the sky one evening at about 6 PM, and directly overhead you see the Moon, half visible, with the left half dark, and the right half illuminated. In about 7 or 8 nights, if you look for the Moon again, you are likely to find that its phase will be...

C. full moon

The collision and interaction of galaxies can occur if they get close enough together. What is responsible for this kind of interaction?

C. gravitational forces

Galileo Galilei's experimental measurements with falling motion are an important part of the scientific method because...

C. his experimental measurements of falling motion are observational evidence for Isaac Newton's theory, The Universal Law of Gravitation

Kepler's 1st Law claims that all planets in our solar system orbit the Sun...

C. in ellipses with the Sun at one focus

Newton's 1st Law helps define an object's mass, by explaining the concept of...

C. inertia

Once a scientific theory has been established, what would need to happen in order to consider changing, abandoning, or replacing it?

C. multiple new observations made by independent scientists would need to contradict the predictions of the theory

Isaac Newton discovered that white light, when passed through a prism, would spread out into a spectrum of all the visible colors of the rainbow. When those colors were passed through a second prism, Newton found that they...

C. recombined to form white light again

The ocean tides on Earth are a result of the gravitational influence of...

C. the Moon and the Sun

Kepler's 2nd Law says that the point in a planet's elliptical orbit around the Sun when it is farthest from the Sun (also called aphelion) is...

C. the place where the planet is moving the slowest

The fastest moving planet in our Solar system is...

C. the planet nearest the Sun

The revolution (orbit) of the Earth about the Sun results in...

C. the yearly cycles of changing hours of daylight and Sun's height in the sky

The two most important components (steps) of the scientific method are...

C. theory and experiment

In a roller coaster you are taken to the top of the tallest hill, then allowed to coast over the rest of the track. At the lowest point on the track...

C. your kinetic energy is a maximum.

In the analogy where an electric circuit is like water flowing through a system of pipes, which circuit component would represent the "storage tank"?

D. the capacitor

Based on its position on an H-R diagram, our Sun is...

D. ...a pretty average, typical main sequence star.

From the H-R diagram, a star about the same temperature as the Sun, but with much higher luminosity would most likely be...

D. ...a supergiant star.

The seasons on Earth result because...

D. Earth's spin axis is tilted 23.5 degrees relative to the ecliptic, causing alternately uneven heating of Earth's northern and southern hemispheres

Which of the following statements is true about the energy levels of atoms?

D. Energy levels are "quantized", meaning they are discrete and well-defined

Which of the following explanations correctly describes the reason we see the Sun rise and set each day?

D. The Earth rotates on its axis

An example of Newton's 3rd Law is...

D. The gravitational force Mars feels from Venus is equal, but opposite in direction, to the gravitational force Venus feels from Mars

A car is parked on a hill. Besides its weight and a frictional force on the tires and brakes, what other force must act in order to keep the car "static"?

D. The normal force: the ground pushing on the car.

An object at the Earth's surface weighs 700 Newtons (about 157 pounds). That object is then transported by spacecraft into orbit 200 miles above the Earth's surface. Which of the following statements below is true?

D. The object's mass has stayed the same, but its weight has decreased

Newton's First Law of Motion states that unless an unbalanced force acts on an object, that object will remain in motion...

D. in a straight line, with constant velocity

Imagine a hanging mass that is connected by a string, over a pulley, to a cart that can roll freely on a horizontal track. Using what you know about Conservation of Energy, the GPE of the falling mass...

D. is converted into both KE of the falling mass and KE of the rolling cart

The most convenient units to use in measuring the distances to stars is...

D. light-years

If the Earth's spin axis were perpendicular to the ecliptic plane (point straight up out of the ecliptic plane, rather than tilted), the seasons on the Earth would...

D. occur mostly at the equator instead of at the poles

Which of the following is NOT a type of galaxy, in the Hubble "tuning fork" classification scheme?

D. starburst

If a star in space is observed in both visible light, and microwaves, and found to be much dimmer in visible light, the most likely explanation for this is...

D. the processes going on in the star produce more microwaves than visible light

The monthly cycle of Moon phases can best be explained by...

D. the revolution of the Moon around the Earth, and the angle of sunlight

If work is done BY a system, what happens to the internal energy of the system?

E. internal energy of the system decreases

Compared to the Sun, main sequence stars with much larger mass...

E. ..."burn" their hydrogen fuel more rapidly than the Sun.

The magnetic field lines produced by a bar magnet... (Check all that apply)

E. ...always begin on the north pole and end on the south pole. F. ...always form closed loops.

The speed of light, c, (measured in meters/second) is...?

E. 300,000,000

Which type of star is most likely to explode as a supernova at some point in the future?

E. A supergiant star

Two ingredients of the scientific method are careful observation, and the development of a model which makes sense of the observations. The history of astronomy and planetary motion in the post-renaissance period provides a beautiful example of this in the cooperation between...

E. Tycho Brahe's observations, and Kepler's Laws

The spiral arms in a galaxy typically contain...

E. all of the above (stars, dust, helium gas, hydrogen gas)

How do electrons in the Bohr model of an atom move between energy levels?

E. by absorbing or emitting only specific sizes (energies) of photons of light

The speed of light is measured to be 3.0 x 108 meters/second, which is...

E. faster than any other known phenomenon

A characteristic of a good scientific theory is that...

E. it is built upon existing knowledge, and testable by experiment

One of the main reasons for the complex system of deferents and epicycles in Claudius Ptolemy's model of the solar system was to try and explain...

E. the observed retrograde motion of Mars

An engineer who designs "static" structures knows that a particular design is a failure if...

E. the structure becomes too dynamic.

When measuring velocity from a graph (like in the first lab, Graphical Analysis), to find the slope of the graph, it is necessary to measure the difference between...

E. two positions at two separate times

During an annular solar eclipse...

F. The Moon covers all but the outer ring of the Sun

During a partial lunar eclipse...

F. The Moon is partially within the Earth's umbra

A "dynamic" system is very desirable when building bridges and buildings.

False

All Helium atoms contain the same number of protons in their nucleus.

True

Frequency and color are two equivalent ways of specifying a type of light wave.

True

Leap year and the Gregorian calendar we use is based on astronomical data.

True

The constellations of the zodiac are more well-known than other star patterns on the celestial sphere, because all 13 constellations lie close to the...

ecliptic

The energy of light is directly proportional to its...

frequency

In a solar eclipse, the dark, inner portion of the Moon's shadow (which may permit someone to view a total solar eclipse), is known as the...

umbra