WGU C451 Module 2: Forces, Energy, and Motion Questions and Answers Rated A+

WGU C451 Module 2: Forces, Energy, and Motion Questions and Answers Rated A+ What is potential energy? Stored energy that has the potential to do work. 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? The greater the mass, the greater the force of gravity it exerts, so the more attracted to each other they will be. When objects are pulled further apart, the force of gravity weakens. The distance increases then the force decreases. What is kinetic energy? Energy due to an object's motion. Explain what happens to kinetic energy when the mass and speed of an object changes. When two objects have the same mass by 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. Thermal Energy Another form of kinetic energy. Thermal energy is the internal energy of an object due to the kinetic energy of its atoms and/or molecules. Law of Conservation of Energy Energy cannot be created or destroyed. Gravitational force Force between two objects that have mass. 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 small the gravitational force between them. What is projectile motion? An object that is projected vertically by some means and continues in motion with its own inertia while gravity acts on the object at the same time and will eventually bring it down to the ground. How does an object become a satellite? When an object orbits around a primary object at a constant distance. The objects horizontal velocity must be great enough for its falling distance to match Earth's curvature. With sufficient tangential velocity, the object does not collide with the primary object it orbits, but maintains a distance from that object as the rate at which it falls towards that object is similar to the rate that it travels away, thus the object orbits the primary object and becomes a satellite. Explain the role of gravity in the formation of solar systems and galaxies. How does gravity create spinning disks of material that form solar systems and galaxies? Orbits of planets, tidal locking, and the sun and stars. Other ways are, classification of planets, dwarf planets, and other objects, orbits of comets, asteroids, and moons, presence of the asteroid belt, subsurface oceans on moons of gas giants. A disc formed by rapidly rotating systems of free particles, bound by gravity. Describe the movement of objects in our solar system. Planets orbit the sun because of gravity. Mercury/Mars don't have enough pull to have an atmosphere. Jupiter/Saturn have a high gravitational pull, they have so many moons and rings because of their mass. The objects are always pulling towards each other. Gravity keeps planets and stars in place and controls their orbits. The planets orbit the sun in the same counter-clockwise direction. Why does the same side of the moon always face the earth? Because the monthly spin rate and orbital revolution rate are the same of the Earth and the Moon. What role does gravity play in the formation of stars? The thermal pressure inside the star far exceeds gravity's ability to hold the star together, and the outer layers of the star evaporate away as planetary nebula. What role does it play throughout the life of a star? Over the course of seconds, gravity pulls the massive outer layers of the star towards the iron and nickel core causing the star to explode as a supernova. What is the relationship between thermal energy and gravitational force in a star? Thermal energy exerts a force from the center of a star outwards. Gravity exerts a force on the outside of a star, pushing inwards towards the center. When these two force balance out, the star has reached its size and mass. How does gravitational field affect light? Light curves in a gravitational field. How will light behave in a black hole? A black hole is so massive that it traps light and any unfortunate matter that happened to get caught in the trajectory leading into the singularity. Newton's Law of Universal Gravitation Between any two objects with mass, there exists a gravitational force between them. Explain what happens to the gravitational force when there is a change in mass and/or distance. If the mass of object 1 increases, does that increase or decrease the gravitational force? - the Gravitational Force would increase. If the distance between objects 1 & 2 increases, does that increases or decrease the gravitational force? - the force when the objects are a distance of 4 apart, is a 25 percent of the force when the objects are at a distance of 2 apart. Coulomb's Law of Electrical Force Two positively charged objects will repel, as will two negatively charged objects. An object with a positive charge and an object with a negative charge will attract. Compare and Contrast Coulomb's Law and Newton's Law Law of Universal Gravitation: A force that acts between objects with mass; only an attractive force. Coulomb's Law: A force that acts between charged objects; can attract or repel. Both: Follow the Inverse Square Law. What are vector and scalar quantities? Vectors: Quantities that have measure of both a magnitude as well as direction. Examples: velocity, force, acceleration, and momentum. Scalars: Quantities that don't have direction, only magnitude. Examples: speed, pressure, mass, energy, and temperature. Inverse Square Law A law stating that the intensity of an effect such as illumination or gravitational force changes in inverse proportion to the square of the distance from the source. Magnetic force Attraction or repulsion that arises between electrically charged particles because of their motion. What makes an object magnetic? Due to moving charges, spinning in the same direction. Electron spin and revolution produce it. Magnetic field The region of magnetic influence around a magnetic pole or around a moving charged particle. How does magnetic force differ from electric force? Magnetic force on a moving charge is always normal to the direction of the movement and the magnetic field whereas the force by an electric field on a moving charge is always parallel to the electric field and does not depend on the direction of movement. What happens to a charged particle in a magnetic field? The charge must be moving. Magnetism will not work on stationary charges. It cannot be moving on a parallel field to the magnetic force. Identify whether each of the following characteristics applies to electricity, magnets, or both. Electricity: Is a flow of charges measured by current, resistance measured in ohms Magnets: Always has a north and south pole. Both: Opposites attract, produced by charged particles that are spinning in the same direction but are not flowing from one atom to another. Newton's First Law An object in motion tends to stay in motion, an object at rest tends to stay at rest, unless acted on by a net force. Newton's Second Law The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object. Newton's Third Law For every action, there is an equal and opposite reaction. Describe what the equation F=MA means and how it relation to Newton's Second Law. The more force you apply, the more acceleration you get out and the more mass that exists, the less acceleration that you get out. Force= Mass x Acceleration; Acceleration= Force/Mass