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Science Unit 4 Test Review
Terms in this set (68)
Short answer: what do magnetic force, gravitational force, and electrical force have in common?
Magnetic force is affected by magnets, gravitatiational force is affected by mass, and electrical rode is effected by charges and they ALL are affected by distance.
Short answer: how are generators different from electrical motors?
Generators take mechanical energy and turn it into electrical energy whereas electric motors use electricity and turns it into mechanical energy.
Short answer: explain the principle of electromagnetic induction?
It's when a magnetic field is induced by movement. It causes or forces it to happen.
Short answer: what is the relationship between voltage across the secondary coil of a transformer and the number of loops it has?
The relationship is a step-up which is from fewer coils to more coils which results in a higher voltage and a step-down which is from more coils to less coils and creates a lower voltage.
Short answer: what are two ways to increase the strength of the magnetic field of a solenoid?
You can increase the number of loops or have a stronger current so that more charges move through at a faster rate.
The transfer of energy as heat caused by the collision of molecules is called?
The temperature at which all molecular motion stops is
C. 0 K
The primary source of the sun's education is
B. Nuclear fission
_______ is the ratio of useful work output to work input.
If a loop of a wire moves in and out of a magnetic field, a _______ is induced.
Temperature is a measure of the average _______ energy of an object's particles.
______ does not involve the movement of matter.
A gasoline engine transforms chemical energy of a fuel into work which is done by
Gravitational potential energy depends on
D. All of the above
A _______ transformer is used near homes to achieve a voltage of 120 V.
The needle of a compass placed near a current-carrying wire will
A. Align with the magnetic field produced by the current
When a pitcher throws a softball to a catcher, the vibration of the atoms that make up the softball is ______ energy, while the motion of the ball toward the catcher is _____ energy.
A. Nonmechanical, mechanical
________ describes how much energy is required to raise an object's temperature
C. Specific heat
According to the first law of thermodynamics,
C. The total energy used in any process is conserved
A transformer changes
B. The voltage of an AC current
The total amount of energy (both usable and unusable) in any process
C. Remains constant
Convection currents rise in air because
B. Cool air descends and hot air rises
An electric motor and a generator are similar in that both
C. Transform energy into a different form
The transfer of energy by the movement of fluids or gases with different temperatures is called
When the loop of a wire in and AC generator rotates halfway,
A. The current reverses direction
A. Mechanical energy to electrical energy
When a charge moves in the same direction as the magnetic field lines, the magnetic force is
Using the following table, determine which substance can absorb the most energy in a temperature increase of 1 K.
A. Liquid water
Which of the following is an example of mechanical energy?
B. Potential energy
Both electric and magnetic fields in an electromagnetic wave are
A. Perpendicular to the direction that the wave travels
Increasing the number of coils in a solenoid or an electromagnet results in a ______ magnetic field
Which of the following is the name of a temperature scale?
D. All of the above
Energy from the sun reaches earth by
B. Radiation only
Which item below contains insulation material?
D. Plastic foam cup
Evaporating causes a _______ effect.
As the kinetic energy of the molecules in a substance increases, the
A. Temperature of the substance increases
The energy transferred between objects with different temperatures is
A dropped racquetball will not return to its original position because
C. Some of the mechanical energy is converted to non mechanical energy
Heat engines use _______ to convert potential chemical energy and internal kinetic energy into mechanical energy.
Which of the following statements about work and energy is NOT true?
C. Work and energy are always equal.
Heat always moves from an object of ______ higher temperature to an object of _______ lower temperature.
B. Higher, lower
When energy is transformed, the amount of usable energy
At the top of its arc, a thrown ball has _______ potential energy
The kind of energy associated with atomic bombs is
C. Chemical energy
An electric motor converts electrical energy into
A. Mechanical energy
A solenoid with a soft iron core is called a(n)
Magnetism is caused by
D. Moving charges
When one feels a warm oven, the sensation of warmth is the result of
A. Energy transfer
The law of conservation of energy states that enerfy
B. Cannot be created or destroyed
The Fahrenheit temperature scale is defined by which of the following temperatures?
B. Water boils at 212 degrees and freezes at 32 degrees
_____ is a measure of the ability to do work.
As a dropped penny falls toward the ground, ______ energy is converted to ____ energy.
D. Potential, kinetic
A device that produces a magnetic field by wrapping wire into a coil is a
The direction of the magnetic field produced by a current-carrying wire can be determined using
A. The right-hand rule
Energy transferred as electromagnetic waves
The movement of fluids due to density differences caused by temperature variations
The transfer of energy as heat through a material
A material through which energy is easily conducted
A material that is a poor conductor of energy
The energy due to motion
C. Kinetic energy
Energy that lies at the level of atoms and that does not affect motion on a large scale
B. Non mechanical energy
The energy of an object due to its position, shape, or condition
A. Potential energy
The sum of an object's kinetic and potential energies
D. Mechanical energy
Essay: using the concept of specific heat, describe the difference in temperature between the water in the pool and the concrete deck on a hot summer day.
Water needs a lot more energy to heat up than the concrete deck. The concrete deck is much hotter than the water because it has a lower specific heat than the water.
Essay:Why do substances expand when energy is added to them as heat?
With heat, the particles which cause more collisions. These collisions then cause the particles to push away from each other and the substance expands.
Essay: Where does energy go when it seems to have disappeared?
When energy seems to have disappeared it really has transferred into other objects through friction. It turns into other forms of energy such as heat, sound, vibrations, and light.
Essay: How does a pendulum show the relationship between gravitational potential energy and kinetic energy?
When a pendulum swings to either side, when it is at its highest point it has the most potential energy. When it is at the lowest point of its swing or at the bottom it has the greatest kinetic energy because it is moving its fastest.
Essay: what is meant by the efficiency of a machine?
The efficiency is he amount of work put into a machine versus what we get out of the machine. A machine will never be 100% efficient because friction takes away from the work we put in.
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