Module 2 : Forces and Energy Flashcards

0
Q

(Forces and Energy Part 1a : Forces and Energy)
Give some examples of different types of :
(A) potential energy
(B) electrical potential energy
(C) chemical potential energy
(D) gravitational potential energy

A

(A) potential energy :
- archer’s bow string pulled back, coiled spring, unopened carbonated drink, child at the top of a slide
(B) electrical potential energy : television before it is turned on, light bulb that is turned off, car headlights before they are turned on, solar cells at night
(C) chemical potential energy :
- charged battery, wick in a candle, gasoline before it’s ignited, fireworks before they are launched
(D) gravitational potential energy :
= mass x acceleration due to gravity x height
- depends on the mass, acceleration due to gravity and height of an object
- stone hanging off the edge of a cliff, me sitting in a chair, any times there is an object above ground has gravitational potential energy

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1
Q

(Forces and Energy Part 1a : Forces and Energy)

What is potential energy?

A
  • the energy a system has due to its shape, position
  • potential energy can be thought of as the potential to do work
  • example : exercise band, the potential energy is increased as the person stretches the band
  • electrical potential energy : thunderstorm, lightning touches the ground
  • chemical potential energy : energy stored in molecular bonds, food, gasoline
  • gravitational potential energy : water being pumped to the top of a water tower
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2
Q

(Forces and Energy Part 1a : Forces and Energy)
How does a change in mass of an object affect the gravitational potential energy of that object? How does a change in height affect it?

A
  • the greater the distance from earth’s center, the less the gravitational force on an object
  • no matter how great the distance, gravity approaches, but never quite reaches zero
  • there is still gravitational attraction between any two masses, no matter how far apart they are
  • gravity gets weaker with distance, the same way a light gets dimmer as you move farther from it
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3
Q

(Forces and Energy Part 1a : Forces and Energy)

What is kinetic energy? List examples of objects with kinetic energy.

A
  • kinetic energy is simply the energy an object has due to its motion
  • anything that is moving has kinetic energy : a moving vehicle, a flowing river, a rolling or spinning ball, a person running, wind, a skydiver falling, a baseball thrown across the field
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4
Q

(Forces and Energy Part 1a : Forces and Energy)

Explain what happens when the mass and speed of an object changes.

A
  • when two objects have the same mass but one object has a greater speed, the object with the greater speed has more kinetic energy
  • when two objects have equal speed, the object with the greater mass has more kinetic energy
  • kinetic energy = (1/2) x Mass x Velocity(squared)
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5
Q

(Forces and Energy Part 1a : Forces and Energy)

Define thermal energy

A
  • thermal energy is just another form of kinetic energy
  • in the case of thermal energy, the molecules within a material have kinetic energy
  • the faster they move, the more thermal energy the molecule has
  • examples : heat of a cup of coffee, fire, your home’s furnace
  • low movement, low temperature; high movement, high temperature
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6
Q

(Forces and Energy Part 1a : Forces and Energy)

Explain the law of conservation of energy.

A
  • states that energy cannot be created or destroyed it can only change form
  • does not apply to nuclear reactions and at quantum (extremely small and short duration) scale
  • when an object burns, it’s chemical energy is being released as thermal energy or infrared radiation
  • states that the total energy released as thermal energy and electromagnetic radiation is equal to the chemical potential energy lost by the burning material
  • roller coaster : maximum potential energy is at the top of the hill, as the rollercoaster moves down the track, potential energy is converted to kinetic energy, the total energy of the rollercoaster remains constant
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7
Q

(Forces and Energy Part 1a : Forces and Energy)

What is gravitational force?

A
  • force between two objects that have mass, in other words, any two objects that have mass will exert a gravitational force
  • the more massive the objects, the greater the gravitational force between them
  • the further the objects are away from each other, the smaller the gravitational force between them
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8
Q

(Forces and Energy Part 1b : Gravity)
What is projectile motion? Give an example of an object that exhibits projectile motion, and describe the forces that are acting on it.

A
  • an object that is projected vertically by some means and continues in motion with it’s own inertia while gravity acts on the object at the same time will eventually bring it down to the ground.
  • vertical velocity decreases as the projectile gets closer to its peak height (kinetic energy is converted to potential energy)
  • horizontal velocity does not change
  • example : water coming out of a water fountain; it shoots up and curved back downs cannon ball fired from a cannon, baseball thrown or hit with a bat, a person jumping on a trampoline, a rock fired from a catapult
  • examples that are NOT projectile motion : rocket, airplane, bird, frisbee
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9
Q

(Forces and Energy Part 1b : Gravity)

How does an object become a satellite?

A
  • is defined as an object in a stable orbit around a larger astronomical body
  • if an object has enough speed, it can escape the earth’s gravitational field rather than enter an orbit or falling back to the earth’s surface
  • this velocity is known as escape velocity
  • the object moves sideways, gravity pulls the object towards the center of the larger object, the object follows an elliptical path as it falls around the larger body
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10
Q

(Forces and Energy Part 1b : Gravity)
Explain the role of gravity in the formation of solar systems and galaxies. How does gravity create spinning disks of material that form the solar systems and galaxies?

A
  • gravity (clouds of dust and materials) within a nebula causes it to slowly collapse
  • eventually the nebula collapses enough to form a star, as the nebula collapses, it’s angular momentum causes a spinning disk to form
  • eventually gravity causes larger chunks in the disk to for; these larger chunks attract more and more material and eventually can form planets; as the protostar grows and continues to collapse due to gravity, eventually it will become massive enough for nuclear fusion to ignite
  • disks are formed of materials bound to an object by gravity
  • orbits of planets, tidal locking, the sun and stars, classification of planets, dwarves, and other objects; orbits of comets, asteroids and moons; presence of the asteroid belt; geological activity on moons of gas giants; subsurface oceans on moons of gas giants
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11
Q

(Forces and Energy Part 1b : Gravity)

Describe the movement of objects in our solar system.

A
  • objects in the inner solar system tend to orbit on a plane
  • most of the planets and larger moons rotate in the same direction
  • comets and objects further out tend to orbit at an incline relative to the inner solar system
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12
Q

(Forces and Energy Part 1b : Gravity)

Why does the same side of the Moon always face the Earth?

A
  • the moon rotates at a speed such that it’s rotation keeps the same side of the moon facing the earth throughout its orbit (synchronous rotation)
  • also explains the rotation of other objects in the solar system : Pluto/Cheron, some moons of Neptune, Uranus, Saturn, Jupiter, and both moons of Mars, possibly Mercury around the sun, also seen in nearby stars
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13
Q

(Forces and Energy Part 1b : Gravity)

What role does gravity play in the formation of stars? What role does it play throughout the life of a star?

A
  • nebula collapses into stars
  • fusion occurs
  • evolves into low mass stars, sun like stars, and/or large mass star
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14
Q

(Forces and Energy Part 1b : Gravity)

What is the relationship between thermal energy and gravitational force in a star?

A
  • thermal energy : exerts a force from the center of a star outwards
  • gravitational force : exerts a force on the outside of a star pushing inwards toward the center
  • when these two forces balance out, the star has reached its size and mass
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15
Q

(Forces and Energy Part 1b : Gravity)

How does a gravitational field affect light?

A
  • I’m 1915 Albert Einstein published his paper on general relativity :
    • gravity has the ability to bend space
    • a photon traveling in a straight line from its perspective will travel in a curved path in the presence of a gravitational field
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16
Q

(Forces and Energy Part 1b : Gravity)

How will light behave in a black hole? Why?

A
  • a black hole is the remains of a super giant star that has collapsed on itself
  • if an object is large enough it can bend space to the point of a singularity
  • if this is the case, then a photon can be trapped in that singularity
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17
Q

(Forces and Energy Part 2a : Coulomb’s Law and Newton’s Law of Universal Gravitation)
Define Newton’s Law of Universal Gravitation. What factors contribute to the strength of a gravitational force?

A
  • every mass pulls on every other mass with a force that is directly proportional to the product of the two interacting masses
  • the force is inversely proportional to the square of the distance separating them
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18
Q

(Forces and Energy Part 2a : Coulomb’s Law and Newton’s Law of Universal Gravitation)
Explain what happens to the gravitational force when there is a change in mass and/or distance.

A
  • the greater the mass, the grater the force of gravity exerts, so the more attracted to each other they will be
  • when objects are pulled further apart, the force of gravity becomes weaker
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19
Q

(Forces and Energy Part 2a : Coulomb’s Law and Newton’s Law of Universal Gravitation)
Define Coulomb’s Law of electrical force. What factors contribute to the strength of an electrical force?

A
  • states that for two charged objects that are much smaller than the distance between them
  • the force between them varies directly as the product of their charges and inversely as the square of the separation distance
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20
Q

(Forces and Energy Part 2a : Coulomb’s Law and Newton’s Law of Universal Gravitation)
Compare and contrast Coulomb’s law and Newton’s law. How are they the same? How are they different?

A
  • similar : they both decrease inversely as a square of distance between charge/mass
  • differ : most important difference is that electrical forces (Coulomb) may be either attractive or repulsive, whereas gravitational forces (Newton) are only attractive
21
Q

(Forces and Energy Part 2a : Coulomb’s Law and Newton’s Law of Universal Gravitation)
What are vector and scalar quantities? Are electrical force and gravitational force vector or scalar?

A
  • vector :
    • quantity having direction as well as magnitude
    • examples : velocity, force, acceleration, momentum
  • scalar :
    • quantity having only magnitude, not direction
    • examples : speed, pressure, mass, energy, temperature, time, length, area, work
  • gravitational force is vector
  • electrical force : electric field strength is vector, electric potential is scalar
22
Q

(Forces and Energy Part 2a : Coulomb’s Law and Newton’s Law of Universal Gravitation)
Describe the inverse-square law (see study sheet for table to fill in)

A
  • SEE PAPER

- a physical law that states a quantity is inversely proportional to square of distance from source of physical quantity

23
Q

(Forces and Energy Part 2a : Coulomb’s Law and Newton’s Law of Universal Gravitation)
How are Newton’s law of universal gravitation and Coulomb’s law examples of the inverse square law?

A
  • Newton’s Law of Universal Gravity : depends on mass
  • Coulomb’s Law of Electrical Force : depends on the charge of particles
  • both have a denominator of distance squared
24
Q

(Forces and Energy Part 2b : Electricity and Magnetism)

What is magnetic force? What makes an object magnetic?

A
  • are created by moving charges

- happens due to moving charges, spinning in the same direction, electrons spin and revolution produce it

25
Q

(Forces and Energy Part 2b : Electricity and Magnetism)

What is a magnetic field?

A
  • place in space near a magnet or electric current where a physical field is created from a moving electric charge that creates force on another moving electric charge
26
Q

(Forces and Energy Part 2b : Electricity and Magnetism)

How does magnetic force differ from electric force?

A
  • magnetic force : larger when objects are closer, exists only when there is moving electric charge, can only attract
  • electric force : larger when objects are closer, exists only when two objects are charger, can repel or attract
27
Q

(Forces and Energy Part 2b : Electricity and Magnetism)

What happens to charged particles in a magnetic field?

A
  • a magnetic field is produced by moving electric charges
28
Q

(Motion)

Describe what the equation F=ma means and how it relates to Newton’s second law.

A
  • force (F) = mass of an object (m) x its acceleration (a)
  • Newton’s second law of motion describes the relationship between an object’s mass and the amount of force needed to accelerate it
  • the more mass an object has, the more force you need to accelerate it
  • the greater the force, the greater the object’s acceleration
29
Q

Unit of force

A
  • also called a Newton
30
Q

Net force

A
  • Combination of all forces on an object
31
Q

equilibrium

A
  • any net force on an object is equal to zero
  • when an object isn’t moving
  • object moving at constant speed
32
Q

Quiz A

What is an example of the law of conservation of energy?

A
  • if a pendulum is one meter off the ground at one end of its swing, it can never be more than one meter off the ground on the opposite end of the swing
  • The law of conservation of energy states that energy cannot be created or destroyed. The pendulum has a specific amount of potential energy at the top of its swing, and it cannot have more potential energy than at the other side of the swing
33
Q

Quiz A

What correctly describes the Earth’s magnetic field?

A
  • it deflects charged particles coming from outer space
  • The Earth’s magnetic field deflects charged particles from outer space. Magnetism is created by moving charges and affects moving charges, so it has no effect on charged particles that are not moving or uncharged particles like meteors even if they are moving
34
Q

Quiz A

What correctly describes the role of gravity in the formation of the solar system?

A
  • gravitational attraction caused matter in nebula to condense ultimately forming the Sun and planets
  • Gravitational collapse of nebular material resulted in a spinning disk that formed the Sun and the inner and outer planets
35
Q

Quiz A

What correctly describes the role of gravity in the Earth-moon system?

A
  • Earth’s gravity causes the moon to elongate, changing its shape
  • The gravitational force that exists between the Earth and the moon causes both bodies to stitch to an oval shape. Tides result when the Earth bulges dues to the gravitational pull of the moon
36
Q

Quiz A

How does the law of universal gravitation differ from Coulomb’s law of electrical forces?

A
  • gravitational force depends on mass whereas electrical force depends on the charge of the particles
  • Coulomb’s law is the relationship between the charge of two particles and the distance between them whereas the law of universal gravitation is the relationship between the mass of two objects and the distance between them
37
Q

Quiz A

What action would increase both the gravitational force and the electrical force?

A
  • half the distance
  • gravitational force and electrical force both follow the inverse-square law. Decreasing the distance between the masses or the electrical charges increases the forces
38
Q

Quiz A

What type of energy is stored within sugar molecules?

A
  • chemical potential energy

- chemical potential energy is stored within the chemical bonds in sugar, gasoline, protein, and other molecules

39
Q

Quiz A

What correctly describes the difference between electrical potential energy and electrical kinetic energy?

A
  • electrical potential energy is energy due to the position of charged particles in a charged sphere while electrical kinetic energy is the movement of charged particles through a wire
  • electrical potential energy depends on the position of the charged particle. Electrical kinetic energy is the movement of electrons
40
Q

Quiz A

What statement correctly describes Newton’s first law of motion?

A
  • an object at rest will remain at rest unless a nonzero force acts on it
  • Newton’s first law states that an object at rest will remain at rest or an object moving at uniform speed will continue moving at uniform speed unless a nonzero force acts on it
41
Q

Quiz A

What is an example of Newton’s second law of motion?

A
  • a heavy car requires more force to accelerate than a light car
  • Newton’s second law describes the relationship between force, acceleration and mass. Heavy cars have more mass that light cars and require more force to accelerate
42
Q

Quiz B

A proton and an electron experience the same amount of electrical force. Which particle accelerates faster?

A
  • the electron, because it has smaller mass
  • both particles experience the same amount of electrical force, but since the electron has a smaller mass, by Newton’s second law, it must accelerate faster
43
Q

Quiz B

What statement correctly describes magnetic force?

A
  • The greatest magnetic force results when charged particles move at right angles to magnetic field lines
  • The motion of charged particles causes them to interact with magnetic fields. When charged particles move at right angles to the magnetic field lines in the force is the strongest, and is weakest when they move parallel to the field lines
44
Q

Quiz B

What is a role of gravity in the Universe?

A
  • Gravity causes the curvature of light in the universe

- Light curves in a gravitational field

45
Q

Quiz B

What explains how gravity affects the universe?

A
  • Gravitational contraction in high mass stars results in fusion reactions that synthesize heavier elements like neon and magnesium
  • When the amount of nuclear fuel in stars decreases, inward gravitational force overcomes outward thermal pressure causing the core to contract and produce enough heat to fuse elements. High mass stars produce enough heat to fuse heavier elements like neon and magnesium
46
Q

Quiz B

What explains the similarity between the law of universal gravitation and Coulomb’s law of electrical forces?

A
  • both formulas are examples of the inverse-square law
  • gravitational force and electrical force both follow an inverse-square law. Both are dependent on the distance between the interacting objects, interacting masses for gravitational force, and interacting charges for electrical force
47
Q

Quiz B

What happens to the gravitational force between two objects when the distance between them is doubled?

A
  • it is one fourth as strong
  • gravitational force is inversely proportional to the distance between the objects squared. Therefore, doubling the distance decreases the force by one fourth
48
Q

Quiz B
What type of energy is the combined total of the translational, rotational, vibrational kinetic energy and potential energy of atoms and molecules?

A
  • thermal energy

- Thermal energy includes both the kinetic and potential energy associated with atoms and molecules that make up matter

49
Q

Quiz B

What describes kinetic energy?

A
  • the kinetic energy is converted to potential energy when a ball is dropped off a cliff
  • An object’s kinetic energy depends on both its mass and speed
50
Q

Quiz B

What law is described by the statement “for every action there is an equal and opposite reaction”?

A
  • Newton’s third law of motion
  • Newton’s third law describes the relationship between two interacting objects. For examples, when a baseball bat hits a baseball the bat exerts a force on the ball and the ball exerts an equal and opposite force back on the bat
51
Q

Quiz B

What is an example of Newton’s first law of motion?

A
  • A seat belt stopping the forward motion of a passenger
  • Newton’s first law states that an object moving at a uniform speed will continue moving at a uniform speed unless a nonzero force acts on it. The bodies of passengers riding in a moving car continue to move forward when a car suddenly stops. A seatbelt is the nonzero force that stops the forward motion