Study Guide for GLO and Final Exam Conceptual Physics
SP1.a Calculate average velocity, instantaneous velocity, and acceleration in a given frame of reference
Topics: Average velocity, instantaneous velocity, acceleration
Average velocity: the change in displacement divided by the change in time.
The slope of the secant line of a displacement-time graph over a given interval.
You should be able to determine speed by displacement over time. An example would be from A to B which is 3 m divided by the time which is equal to 3 s so the speed is 1m/s.
Problems:
1. What is the speed of the cart from A to C?
2. What is the speed of the cart from C to E?
· Instantaneous velocity: (v=∆s/∆t) The derivative of the displacement-time graph function at a given point.
· Acceleration (a vector quantity) is the rate of change of velocity in a given direction (in m/s/s of m/s2).
SP1.b Compare and contrast scalar and vector quantities.
Topics: Scalar, vector
· Velocity (a vector quantity) is speed in a given direction (m/s)
· Displacement (a vector quantity) is a measured distance in a given direction in ().
· Speed (a scalar quantity) is the rate at which a moving object covers distance in (m/s)
To have a scalar quantity, you do not have direction (distance, time)
SP1.c Compare graphically and algebraically the relationships among position, velocity, acceleration, and time.
Topics: Position, velocity, acceleration, time
In one dimension, velocityis almost exactly the same as what we normally call speed.The speed of an object (relative to some fixed reference frame) is a measure of "how fast" the object is going--and coincides precisely with the idea of speed that we normally use in reference to a moving vehicle. Velocity in one-dimension takes into account one additional piece of information that speed, however, does not: thedirectionof the moving object. Once a coordinate axis has been chosen for a particular problem, thevelocityvof an object moving at a speedswill either bev=s, if the object is moving in the positive direction, orv= -s, if the object is moving in the opposite (negative) direction. (http://www.sparknotes.com/physics/kinematics/1dmotion/section2.rhtml)
http://hyperphysics.phy-astr.gsu.edu/hbase/mechanics/motgraph.html
SP1.d Measure and calculate the magnitude of frictional forces and Newton’s three Laws of Motion.
Problem: What are Newton’s three laws of motion?
1. An object in motion stays in motion and an object at rest stays at rest unless acted upon by an outside force.
2. Net force is equal to mass times acceleration (F=ma).
3. For every action force there is an equal and opposite reaction.
· Example of Newton’s first law: A ball rolling down a ramp onto a smooth (frictionless) surface will continue to roll forever unless an external force acts on it.
· A zookeeper has to lift a lion on a stretcher at certain acceleration so the force must be equal to the mass of the stretcher and the lion times the acceleration needed.
· Example of Newton’s third law: Two ice skaters push off of each other. They both slide backwards.
SP1.e Measure and calculate the magnitude of gravitational forces.
Topics: gravitational force
Newton’s Law of Universal Gravitation
Every body attracts every other body with a force, which is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers of mass.
SP1.f Measure and calculate two-dimensional motion (projectile and circular) by using component vectors.
• A scalar is a quantity that can be completely specified by its magnitude
• A vector is a physical quantity that has both magnitude and direction.
• Some examples of vector quantities are velocity, acceleration, displacement and forces.
• Vectors can be added graphically, but when adding vectors you must be sure that they have the same units and that the vectors describe similar quantities.
• The answer found by adding vectors is called the resultant.
The magnitude and direction of the resultant of two perpendicular vectors can be calculated using the Pythagorean Theorem and the tangent function.
Magnitude of vector → Pythagorean Theorem
Direction of vector → Tangent function
Eg. A person walks 4 blocks north then one block southeast. What is the displacement and direction of the person? A2 + B2 = C2 42 + 12 = C2 C= 4.123 NE
SP1.g Measure and calculate centripetal force.
Topics: Centripetal force
Gravity provides the centripetal force for objects to remain in motion around another object (eg. Our moon circles the earth as a satellite. There are many man-made objects that do the same thing.).
The net force to provide for uniformed circular motion is centripetal acceleration.
F= mass x velocity2 divided by the radius of the circle
Eg. An object orbiting a planet has a mass of 100kg and a velocity of 320m/s. The diameter of the planet is 9.67x106m. What is the centripetal force?
F= 100 x (320 2) / (4.84 x106)= 2.116 N
Problems:
1. A person who weighs 83kg is on an amusement park ride traveling at a speed of 3.2m/s has a force of 560N pressing against his back. What is the radius?
2. A speed skater goes around a turn with a 31m radius at a velocity of 6m/s. What is the mass of the skater if the force is 56N?
F= mass x velocity2 divided by the radius of the circle
SP1.h Determine the conditions required to maintain a body in a state of static equilibrium.
Topics: Static equilibrium
Definition: Static equilibrium refers to objects that are not moving. There are many objects that we would like to have in static equilibrium; your kitchen cabinets or bedroom wall, for example. If an object is in static equilibrium, there are two very specific things the object is not doing that are important to understand. It is neither translating nor is it rotating. The first condition, no translation, requires that the net force (meaning the sum of all forces) acting on the object must be zero. The second condition, no rotation, requires that the net torque or moment also be zero.
If a boy is pushing on a wall while standing on a floor, there are equal forces at work.
The boy’s force =wall force
Gravity is pushing down as much as the floor is pushing up. Net force is zero.
SP2.a Relate the energy produced through fission and fusion by stars as a driving force in the universe.
Topics: fission, fusion
Nuclear Fission / Nuclear Fusion /Definition: / Fission is the splitting of a large atom into two or more smaller ones. / Fusion is the fusing of two or more lighter atoms into a larger one.
Natural occurrence of the process: / Fission reaction does not normally occur in nature. / Fusion occurs in stars, such as the sun.
Byproducts of the reaction: / Fission produces many highly radioactive particles. / Few radioactive particles are produced by fusion reaction, but if a fission "trigger" is used, radioactive particles will result from that.
Conditions: / Critical mass of the substance and high-speed neutrons are required. / High density, high temperature environment is required.
Energy Requirement: / Takes little energy to split two atoms in a fission reaction. / Extremely high energy is required to bring two or more protons close enough that nuclear forces overcome their electrostatic repulsion.
Energy Released: / The energy released by fission is a million times greater than that released in chemical reactions; but lower than the energy released by nuclear fusion. / The energy released by fusion is three to four times greater than the energy released by fission.
Nuclear weapon: / One class of nuclear weapon is a fission bomb, also known as an atomic bomb or atom bomb. / One class of nuclear weapon is the hydrogen bomb, which uses a fission reaction to "trigger" a fusion reaction.
· Nuclear fission: process in which a heavy nucleus splits up into lighter nuclei.
· Large amounts of energy produced, can be self-sustaining due to chain reactions.
· Nuclear fusion: joining of two light nuclei into a heavier one.
All elements were formed by the joining of simple elements into more complex ones. Our sun does this as it burns and gives electromagnetic waves.
SP2.b Explain how the instability of radioactive isotopes results in spontaneous nuclear reactions.
Topics: Radioactive isotopes, nuclear reactions
· An isotopic form of an element with an unstable nucleus that stabilizes itself by emitting ionizing radiation.
· A reaction, as in fission, fusion, or radioactive decay, that alters the energy, composition, or structure of an atomic nucleus.
· the spontaneous disintegration of a radioactive substance along with the emission of ionizing radiation.
Particle / Alpha () / Beta () / Gamma ()Nature / Helium nucleus / Electron / Photon
Charge / +2e / -e / 0
Mass / 4u / 1/1850 u / 0
Penetrative power / A few cm of air
Stopped by a sheet of paper / A few mm of metal
Stopped by a cinderblock / Many cm of lead- stopped by 2 feet of lead
Magnetic fields / Is affected / Is affected / Not affected
SP3.a Analyze, evaluate, and apply the principle of conservation of energy and measure the components of work-energy theorem by
• describing total energy in a closed system.
• identifying different types of potential energy calculating kinetic energy given mass and velocity.
• relating transformations between potential and kinetic energy
Topics: potential energy, kinetic energy, closed system, open system
Potential energy= energy of position
Gravitational potential energy = mass of the object x gravity x height of the object
Eg: A rock with mass 370g sits above a valley at a height of 21meters. What is the gPE of the object? The constant for gravity is 9.81m/s2
370g x 21m x 9.81m/s2
The SI unit for gPE is J
Kinetic Energy= ½ mv2 and is measured in J
The work energy theorem may be derived for any direction of the force relative to the displacement. A moving object has kinetic energy, because work was done accelerate the object from rest to a speed. An object with kinetic energy can perform work.
· Thermal energy of a system is referred to as internal energy—the sum total of the potential energy and kinetic energy of the particles making up the system.
· Closed systems, on the other hand, are held to be isolated from their environment.
· The open systems are systems that allow interactions between its internal elements and the environment. An open system is defined as a “system in exchange of matter with its environment, presenting import and export, building-up and breaking-down of its material components.
Eg: a space probe with mass of 50000 kg is traveling at a speed of 1.1x 104. What is its KE?
(1/2)(50000)(1.1x104)2 = 3.025 x1012 J
Problems for KE and PE
1. A 65kg rock climber ascends a cliff. What is the climber’s gravitational potential energy at a point 35m above the base of the cliff?
2. What is the KE of a cheetah running at a speed of 31m/s?
3. A 35kg child has 190J of KE after he sleds down a hill. What is the child’s speed at the bottom of the hill?
SP3.b Explain the relationship between matter and energy.
Topics: matter, energy
Matter= anything that has mass and takes up space
Energy= the ability to do work
Matter and energy are interchangeable, but neither matter no energy can be destroyed or created.
(E=mc2)
Energy is equal to mass time the speed of light squared.
SP3.c Measure and calculate the vector nature of momentum.
Topics: momentum
· The rate of change of linear momentum of a particle is directly proportional to the impressed force acting upon it and takes place in the direction of the impressed force.
· p=mass x velocity
Eg:
1. A 19kg motorcycle is moving at 9m/s. What is its momentum? 19 x 9=171kg-m/s or 171N
2. If the same motor cycle, crashed into a wall causing it to stop in 0.05s, what will the force be? 19kg from the above problem is the mass. 9m/s was the velocity. If the formula is used for force then F=m x a or (19kg) (0-9m/s/ 0.05s)
19kg x 180m/s2 = -3420.
SP3.d Compare and contrast elastic and inelastic collisions.
Topics: elastic and inelastic collisions
· Elastic collisions are collisions in which mechanical energy is not lost.
· Inelastic collisions are collisions in which mechanical energy is lost.
SP3.e Demonstrate the factors required to produce a change in momentum.
Topics: vector, momentum
For an object to have momentum, some force must have set it in motion, and that force must have been applied over a period of time, likewise, when the object experiences a collision or any other event that changes its momentum, that change may be described in terms of a certain amount of force applied over a certain period of time. Force multiplied by time interval is impulse, expressed in the formulaF· δt,whereFis force, δ (the Greek letter delta) means "a change" or "change in…"; andtis time.
A collision could be a way to change momentum.
SP3.f Analyze the relationship between temperature, internal energy, and work done in physical system.
Topic: Internal energy, temperature, work
· Temperature is a measure of the average kinetic energy of the molecules of a substance.
· Internal Energy is the thermal energy of a system—the sum total of the potential energy and kinetic energy of the particles making up the system.
· Heat is the thermal energy that flows from one (high temperature) body to another (of lower temperature).
· Any time work is done some of the energy put in to do the work is lost as heat.
SP3.g Analyze and measure power.
Topic: power
Power is the rate at which work is performed or the rate at which energy is transmitted.
Power is equal to work/ time.
SP4.a Explain the processes that results in the production and energy transfer of electromagnetic waves.