physics test 3
How much time does it take for a complete revolution of a satellite in close orbit about Earth?
90 minutes
Why aren't heavier elements much larger than lighter elements?
The larger positive charge in the nucleus pulls the electrons into closer orbits.
Why do we say that a blob of putty is inelastic?
When deformed, it does not return to its original shape.
Compared to the volume of a kilogram of feathers, the volume of a kilogram of lead is
less
Suppose you increase the depth of the object WITHOUT changing its height. What will happen to the force due to pressure on the bottom of the object?
the force due to pressure on the bottom of the object will increase
Suppose you increase the height of the object WITHOUT changing its depth under water. What will happen to the force due to pressure on the bottom of the object?
the force due to pressure on the bottom of the object will increase
Why doesn't the force of gravity change the speed of a bowling ball as it rolls along a bowling lane?
the force is at a right angle to the motion
Why doesn't the force of gravity change the speed of a satellite in circular orbit?
the force is at a right angle to the motion
Suppose you increase the height of the object WITHOUT changing its depth under water. What will happen to the net buoyant force?
the net buoyant force will increase
Which projectile spends more time in the air, the one fired from 30* or the one fired from 60*?
the one fired from 60*
For orbits of greater altitude, is the period longer or shorter? Is the speed faster or slower?
the period is longer and the speed is slower
What happens to the pressure in all parts of a confined fluid if the pressure in one part is increased?
the pressure everywhere increases by the same amount
If you swim beneath the surface in saltwater, will the pressure be greater than in fresh water at the same depth?
the pressure will be greater
How does the water pressure 1 m below the surface of a small pond compare with the water pressure 1 m below the surface of a huge lake?
the pressure will be the same
how can a projectile "fall around the earth"?
-A projectile can "fall around Earth" if the distance it falls matches the curvature of Earth. -The projectile falls 5 m for every 8 km and so does Earth. -In a circular orbit around a spherical planet, the force and the fall are always toward the center.
If a fictional shrinking man shrinks proportionately to 1/10 his original height, his weight will be multiplied by
.001
What is the volume of a sugar cube that measures 1 cm on each side? What is the cross-sectional area of the cube? The total surface area?
1 cm3, 1 cm2, 6 cm2
Which contains more atoms? 1 kg of iron or 1 kg of hydrogen?
1 kg of hydrogen
A projectile is launched vertically at 100 m/s. If air resistance can be ignored, at what speed will it return to its initial level?
100 m/s
What is the mass density of water? What is the weight density of water?
1000 kg/m3; 9800 N/m3
Escape speed from Earth is any speed equal to or greater than __________.
11.2 km/s
If the linear dimensions of an object are doubled, by how much does the surface area increase? By how much does the volume increase?
4 times, 8 times
A projectile falls beneath the straight-line path it would follow if there were no gravity. How many meters does it fall below this line if it has been traveling for 1 s? For 2 s?
5 m, 20 m
How far does a projectile drop in 1 second? What is the speed needed for a projectile to orbit Earth?
5 m, 8 km/s
How far below a straight-line path does a horizontally projected projectile fall in the first second of fall?
5 meters
If a 1-kg object stretches a spring by 2 cm, then how much will the spring be stretched when it supports a 3-kg object? (Assume the spring does not reach its elastic limit.)
6 cm
A projectile is launched at 30° above ground level. What other angle at the same speed will result in the same range?
60*
If an elephant grows proportionally to twice its height, its weight would be multiplied by about
8
How does a molecule differ from an atom? Give an example.
A molecule is composed of two or more atoms bonded together: H2O.
Distinguish between tension and compression.
A pulled-apart object is in tension; a pushed-together one is in compression.
What is meant by the elastic limit for a particular object?
A spring is elastic up to the limit and inelastic above it.
distinguish between adhesive and cohesive forces
Adhesive forces are between unlike substances, whereas cohesive forces are between like substances.
How does the arrangement of atoms in a crystalline substance differ from the arrangement in a noncrystalline (amorphous) substance?
Atoms in crystals are in an ordered array. In amorphous materials, they are randomly distributed.
What is a mixture? Cite two examples.
Atoms pressed together without bonding: air and salt and sand
Who gathered the data that showed planets traveling in elliptical paths around the Sun? Who discovered elliptical orbits? Who explained them?
Brahe, Kepler, Newton
If you want to light some wood on fire, what would most likely make the wood light, and why?
Breaking the log down into small pieces of wood will increase the amount of wood surface that can catch fire.
What are the five most common elements in humans?
C, H, O, N, and Ca
If you want to cool down a drink with ice, which of the following would make it cool faster and why?
Crushing the lump into small pieces will put more of the ice's surface area is in contact with the drink.
What is the evidence that dark matter exists?
Gravitational forces within galaxies are too great to be accounted for with ordinary matter.
Why does the force of gravity change the speed of a satellite in an elliptical orbit?
Gravity slows the satellite as it moves away and speeds it up on its return.
Distinguish between mass number and atomic mass.
Mass number is the number of nucleons; atomic mass is the total mass of an atom.
What is Hooke's law? Does it apply to elastic materials or to inelastic materials?
Stretch is proportional to force for elastic materials.
Why is kinetic energy a constant for a satellite in a circular orbit but not for a satellite in an elliptical orbit?
The force of gravity is perpendicular to the motion in a circular orbit but not in an elliptical orbit.
What and where is the neutral layer in a beam that supports a load?
The layer in which there is neither tension nor compression along the middle from end to end
Which of the following items would remain without rusting longer: a solid lump of steel, or steel wool that weighs the same amount?
The lump of steel would stay without rusting longer, because not as much of it comes in contact with the air.
What did Kepler discover about the periods of planets and their distances from the Sun?
The period squared was proportional to the distance cubed
Why do French fries cook faster when they are cut into thinner pieces, and why do meatballs cook faster when they are flattened?
There is a greater amount of surface area for the same amount of food in the thinner fries and flattened meatballs.
Why are the cross-sections of metal beams in the shape of the letter I instead of solid rectangles?
To reduce the weight of the beam while preserving the resistance to bending
How does the height to which water is lifted in a capillary tube relate to adhesion and the weight of the water lifted?
Water rises to a height where the adhesive forces equal the weight of the water lifted.
Why do we say that a spring is elastic?
When deformed, it returns to its original shape.
What evidence can you cite for the microscopic crystal nature of certain solids? For the macroscopic crystal nature?
X-ray diffraction and the macroscopic shape of crystals
What is meant by the term nucleon?
a proton or neutron
What is the purpose of a model in science?
abstraction that helps us visualize and predict
As the text cites, atoms are incredibly tiny, numerous, perpetually moving, and what else?
ageless
Which of the following is stronger per bodyweight?
an ant
Which of the following has the greatest outer surface area?
an elephant
Water pressure in a lake is greater __________.
at the bottom
Why can't atoms be seen with a powerful optical microscope?
atoms are much smaller than wavelength of light
The crew of a cargo plane wishes to drop a crate of supplies on a target below. To hit the target, when should the crew drop the crate? Ignore air resistance.
before the plane is directly over the target
Is the sum of kinetic and potential energies a constant for satellites in circular orbits, in elliptical orbits, or in both?
both
The name given to the shape of a sagging rope supported at its ends is a __________.
catenary
The kinetic energy of a satellite remains constant when the satellite follows a __________.
circular path
What causes dust particles and tiny grains of soot to move with Brownian motion?
collisions with invisible molecules
Is it tension or compression that strengthens an arch that supports a load?
compression
What does the strength of a person's arm usually depend on?
cross sectional area
While a rock thrown upward at 50 degrees to the horizontal rises, neglecting air drag, its vertical component of velocity
decreases
A stone is thrown upward at an angle. What happens to the magnitude of the vertical component of its velocity as it rises? As it falls?
decreases while rising, increasing while falling
What happens to the volume of a loaf of bread that is squeezed? The mass? The density?
decreases, stays the same, increases
How does one isotope differ from another?
different number of neutrons
While an airplane flies at 40 m/s at an altitude of 500 meters, the pilot drops a heavy package that falls to the ground. Neglecting air drag, about where does the package land relative to the plane flying above?
directly beneath the plane
The pressure increases on a block resting on a table when you increase the __________.
downward force on the block
What kind of attraction pulls electrons close to the atomic nucleus?
electric
What type of force holds atoms together in a crystal?
electric
Which of the following are negatively charged?
electrons
Which has more skin: an elephant or a mouse? Which has more skin per unit of body weight: an elephant or a mouse?
elephant, mouse
Which requires more food daily: an elephant or a mouse? Which requires more food per unit of body weight: an elephant or a mouse?
elephant, mouse
Kepler was the first to be credited for discovering that planets follow __________.
elliptical paths
In a hydraulic-press operation, it is impossible for the
energy output to exceed the energy input
Which of the following has the greatest density?
gold
Which of these atoms has the largest number of neutrons in the nucleus?
gold
When air resistance is neglected, why does the vertical component of velocity for a projectile change with time, whereas the horizontal component of velocity doesn't change?
gravity is a purely vertical force
At what part of an elliptical orbit does an Earth satellite have the greatest speed? The lowest speed?
greatest nearest earth; lowest furthest from earth
One neutron added to a helium nucleus results in
helium
The electrical force is stronger between the nucleus and an inner electron for atoms of
high atomic number
What element has the lightest atoms?
hydrogen
What is the most abundant element in the known universe?
hydrogen
Which of the following is an element?
hydrogen
Where in the atom is most of its mass concentrated? What is this mass composed of?
in the nucleus as protons and neutrons
The horizontal and vertical components of velocity for a projectile are __________.
independent of each other
How does the electric charge of a proton compare with the electric charge of an electron?
it is equal and opposite
Is the buoyant force on a submerged object equal to the weight of the object itself or is it equal to the weight of the fluid displaced by the object?
it is equal to the weight of the fluid displaced
A ball is thrown upward and caught when it returns. Compared with its initial speed and in the presence of air resistance, the speed with which it is caught is
less
Pascal's principle applies to
liquids & gases
Surface tension is caused by __________.
molecular attractions
Are most of the atoms around us younger or older than the Sun?
most are older than the sun
Dr. Chuck projects a ball horizontally from a lab bench. The ball lands on a bullseye marked on the floor a horizontal distance equal to the ball's initial speed
multiplied by its time in the air
The charge in the nucleus of an antimatter hydrogen atoms is __________.
negative
Two protons added to an oxygen nucleus produce
neon
When a tree branch is bent, the region in the center of the branch is the __________.
neutral layer
do speed, momentum, kinetic energy vary in circular orbits?
no
How are most of the elements with nuclei heavier than those of hydrogen and helium formed?
nuclear fusion in stars
What does the atomic number of an element tell you about the element?
number of protons in its nucleus
Although solid matter is mostly empty space, we don't fall through the floor because
of electrical forces
The foci of the elliptical path for an Earth satellite are _________
one at earth's center and the other elsewhere
Eight little spheres of mercury coalesce to form a single sphere. Compared to the combined surface areas of the eight little spheres, the surface area of the big sphere is
one half
For an Earth satellite in circular orbit, list all the values that do not change.
only speed, gravitational force, and distance from earth
The number of protons in a neutral atom is balanced by an equal number of
orbital electrons
A rocket coasts in an elliptical orbit about Earth. To attain escape velocity using the least amount of fuel in a brief firing time, should it fire off at the apogee, or at the perigee? (Hint: Let Fd = KE guide your thinking.)
perigee, where it is closest and fastest
Dark matter is considered to be __________.
plentiful in the universe
What is the relationship between liquid pressure and the depth of a liquid? Between liquid pressure and weight density?
pressure is proportional to depth and weight density
How does pressure at the bottom of a body of water relate to the weight of water above each square meter of the bottom surface?
pressure is the weight of the water divided by 1 m^2
How does pressure relate to force?
pressure= force per unit area
While a rock thrown upward at 50 degrees to the horizontal rises, neglecting air drag, its horizontal component of velocity
remains unchanged
A stone is thrown upward at an angle. What happens to the horizontal component of its velocity as it rises? As it falls?
rising or falling, it does not change
Which is denser: an object that has a density of 1000 kg/m3 or one that has a density of 1 g/cm3?
same density
For an Earth satellite in an elliptical orbit, list all the values that do change.
speed, gravitational force, and distance from earth
Which of these vary for satellites in elliptical orbits?
speed, momentum, kinetic energy
What geometrical shape has the smallest surface area for a given volume?
sphere
Why were so many vertical columns needed to support the roofs of stone buildings in ancient Egypt and Greece?
stone breaks under tension
Why isn't cement needed between the stone blocks of an arch that has the shape of an inverted catenary?
stones are held together by compressive forces
What occurs when a proton and an antiproton meet?
they annihilate each other
According to Hooke's law, if you double the force when stretching a spring, the elongation of the spring is normally __________.
twice as much
A stone submerged in water displaces the _________.
volume of water
Why can atoms be seen with an electron beam?
wavelength of electrons is smaller than atom
Why aren't vertical columns needed to support the middle of domed stadiums, such as the Houston Astrodome?
weight produces compression that supports the dome
