Two balls, one mass 5 kg and the other mass 10 kg, are dropped simultaneously from a window. When they are 1 m above the ground, the balls have the same
A 150 kg yak has an average power output of 120 W. The yak can climb a mountain 1.2 km high in
Car A has a mass of 1000 kg and is moving at 60 km/h. Car B has a mass of 2000 kg and is moving at 30 km/h. The kinetic energy of car A is
twice that of car B
A 1 kg object has a potenital energy of 1 J relative to the ground when it is at a height of
The 2 kg blade of an ax is moving at 60 m/s when it strikes a log. If the blade penetrates 2 cm into the log as its KE is turned into work, the average force it exerts is
A 1 kg ball is thrown in the air. When it is 10 m above the ground, its speed is 3 m/s. At this time m0st of the ball's total energy is in the form of
A 10,000 frieght car moving at 2 m/s collides with stationary 15,00 kg freight car. The two cars couple together and move off at
A 30 kg girl and a 25 kg boy are standing on frictionless roller skates. The girl pushes the boy, who moves off at 1.0 m/s. The girls speed is
(W) a process that transfers energy to an object when an object is moved against an opposing force or from rest.
types of energy
-Mechanical- potential and kinetic (push, pull, drop)
-Electrical- energy of moving charges Ex: used to turn motors
-Radiant- energy that travels through space Ex: from the sun
-Nuclear- changes in the nucleus of an atom
law of conservation of momentum
in the absence of outside forces, the total momentum of a set of objects remains the same no matter how the objects interact with one another.
the rush of the gases out of the rockets is balanced by the rocket moving upward and thus the total momentum of the entire system=zero!
the measure of the tendency to keep spinning at the same speed in the same direction
a spinning body tends to maintain the direction of its spin axis as well as the amount of angular momentum
a relative measure of the amount of heat in a substance. Also, the property that gives rise to sensations of hot and cold.
(unit=Joule) the sum of all kinetic energies of all the separate particles that make up an object (also called initial energy)
specific heat capacity
(unit= kj/kg*C) the amount of heat that must be added to or removed from an object to change its temperature by 1 degree C. Q=mc(change in temp).
the biochemical processes by which the energy content of food an animal eats is liberated
(Fb) the difference between the force pulling down on the object (gravity) and the force pushing up on the object (fluid pressure)
buoyant force on an object in a fluid = weight of fluid displaced by the object.
- This principle holds if the object sinks or floats.
- If the object's weight is greater than the buoyant force, it sinks vice versa
at a constant T and n, the V of any gas is inversely proportional to the applied (external) P on the gas.
ideal gas law
is a mathematical expression relating Boyle's, Charles's and Gay-Lussac's laws at constant number of moles. P1V1/T1=p2V2/T2
kinetic theory of matter
the energy of molecular motion; it is the energy that tends to disorganize matter.
a device that turns heat into mechanical energy. Ex: gasoline engine or steam turbine at a power plant
first law of thermodynamics
energy cannot be created nor destroyed only converted from one form to another.
second law of thermodynamics
it is impossible to take heat from a source and change all of it to mechanical energy or work; some heat must be wasted.
if we connect a wire between the + and - terminals of a battery we get an electrical circuit. The flow of electrons can be measured as a rate which is called an ampere.
a substance through which electric charge has a difficult time (no to little conductivity). Ex: glass, rubber, plastic, sand, dirt, wood.
in between a conductor and an insulator in its ability to conduct electricity. Semiconductors are used to make transistors, which are devices that can be used as a tiny switch in electrons. Ex: Silicon, germanium
the altered space around a mass (gravity force), and electric charge (electrostatic force), or a magnet force (magnetic force).
he noticed that a compass lines up perpendicular to a wire with current running through it. All moving electric charges give rise to magnetic fields!
right hand rule
if we point our thumb on our right hand in the direction of the current flow, our fingers point in the direction of the magnetic field.
Two thermometers, one calibrated in degrees F and the other in degrees C, are used to measure the same temperature. The numerical reading on the fahrenheit thermometer
may be any of these, depending on the temperature
One gram of steam at 100 degrees C causes a more serious burn than 1 g of water at 100 degress C because steam
contains more energy
The pressure of the earths atmosphere at sea level is due to
the gravitational attraction of the earth for the atmosphere
A cake of soap placed in a bathtub of water sinks. The buoyant force on the soap is
less than its weight
The density of freshwater is 1.00 g/cm3 and that of seawater is 1.03 g/cm3. A ship will float
lower in freshwater than in seawater
An icecube whose center consists of liquid water is floating in a glass of water. When the ice melts, the level of water in the glass
remains the same
A person stands on a very sensitive scale and inhales deeply. The reading on the scale
any of the above, depending on how the expanision of the persons chest compares with the volume of air inhaled
At constant pressure the volume of a gas sample is directly proportional to
its absolute temperature
absolute zero may be regarded as that temperature at which
molecular motion in a gas would be minimum possible
the temperature of a gas sample in a container of fixed voume is raised. The gas exerts a higher pressure on walls of its container because its molecules
have higher average velocities and strike the walls more often
The volume of a gas sample is increased while its temperature is held constant. The gas exerts a lower pressure on the walls of its container because its molecules strike the walls
When evaporation occurs, the liquid that remains is cooler because
the slowest molecules remain behind
Food cooks more rapidly in a pressure cooker than in an ordinary pot with a loose lid because
the high pressure raises the boiling poinht of water
A heat engine takes in heat at one temperature and turns
some of it into work and ejects the rest at a lower temperature
In any process the maximum amount of heat that can be converted to mechanical energy
depends on the intake and exhaust temperatures
The seconmd law of thermodynamics does not lead to the conclusion that
the total amopunt of energy in the universe including rest energy is constant
An object suspended from a spring scale is lowered into a pail filledd to the brim with water; and 4 N of water overflows. The scale shows that the object weighs 6 N in the water. The weight in air of the object is
At which of the following temperatures would the molecules of a gas have twice the average kinetic energy they have at room temperature, 20 degrees C
313 degrees C
A heat engine absorbs heat at a temperature of 127 degrees C and exhausts heat at a temperature of 77 degrees C. Its maximum efficiency is
A positively charged rod is brought near an isolated metal ball. Which of the sketches best illustrates the arrangement of charges on the ball?
Coulumb's Law for the force between electric charges belongs in the same category as
Newtons law of gravitation
The electric force between a proton and an electron
is stronger than the gravitiational force between them
a drawing of the field lines of magnitude field provides information on
both the direcion and the strength of the field
magnetic field lines provide convenient way to visualize a magnetic field. Which of the following statements is not true?
the path followed by an electric charge released near a magent corresponds to a field line
the magnetic field of a bar magnet resembles most closely the magnetic field of
a wore loop carrying a direct current
a current carrying wire is in a magnetic field with the direction of the current the same as that of the field
the wire has no tendency to move or to turn