Physics semester 1 final study guide
State Newton's Second Law and apply it to situations involving force, mass, and acceleration.
Isaac Newton's First Law of Motion states, "A body at rest will remain at rest, and a body in motion will remain in motion unless it is acted upon by an external force." What, then, happens to a body when an external force is applied to it? That situation is described by Newton's Second Law of Motion. It states, "The force acting on an object is equal to the mass of that object times its acceleration." This is written in mathematical form as: F=ma
Show how the impulse in a system is related to the change in momentum
they are the same but impulse is in N
Determine the unique speed of a satellite, given it height above the center of the Earth or Moon or planet.
http://www.physicsclassroom.com/class/circles/Lesson-4/Mathematics-of-Satellite-Motion
Calculate momentum changes in inelastic collisions, using the concept of Conservation of Momentum.
m1 times v1= -m2xv2
Determine the change in momentum of a body and relate to an impulse
mass x velocity
velocity
measure the distance that the object travels in metres. measure the time it takes for the object to travel that distance.
Describe or sketch the force vectors and their components at work in a given situation, such as a block sliding on an inclined plane.
normal force are alway directed perpendicular to the surface .physicsclassroom.com/class/vectors/Lesson-3/Inclined-Planes
Be able to draw a free-body diagram which includes all forces on an object.
gravity is down and force is where there is
Break forces down into perpendicular components, using sines and cosines.
http://www.physicsclassroom.com/calcpad/vecforce
Determine the centripetal acceleration and force in a system, given suitable information.
http://hyperphysics.phy-astr.gsu.edu/hbase/cf.html
Determine the mechanical advantage of a particular machine (e.g. a lever).
A machine is a device that does work. Most machines consist of a number of elements, such as gears and ball bearings, that work together in a complex way. Nonetheless, no matter how complex they are, all machines are based in some way on six types of simple machines. These six types of machines are the lever, the wheel and axle, the pulley, the inclined plane, the wedge, and the screw. Principles of Simple Machines: Machines simply transmit mechanical work from one part of a device to another part. A machine produces force and controls the direction and the motion of force, but it cannot create energy. A machine's ability to do work is measured by two factors. These are (1) mechanical advantage and (2) efficiency. Mechanical advantage. In machines that transmit only mechanical energy, the ratio of the force exerted by the machine to the force applied to the machine is known as mechanical advantage. Under mechanical advantage the distance the load will be moved will be only be a fraction of the distance through which the effort is applied. While machines can provide a mechanical advantage of greater than 1.0 (and even less than 1.0 if desired), no machine can never do more mechanical work than the mechanical work put into it. Efficiency. The efficiency of a machine is the ratio between the work it supplies and the work put into it. Although friction can be decreased by oiling any sliding or rotating parts, all machines produce some friction. A lever has a high efficiency due to the fact that it has low internal resistance. The work it puts out is almost equal to the work it receives, because energy used up by friction is quite small. On the other hand, an a pulley might be relatively inefficient due to a considerably greater amount of internal friction. Simple machines always have efficiencies of less than 1.0 due to internal friction. Energy conservation. Ignoring for a moment the losses of energy due to friction, the work done on a simple machine is the same as the work done by the machine to perform some sort of task. If work in equals work out, then the machine is 100% efficient.
Distinguish between scalar and vector quantities.
A scalar quantity is a one dimensional measurement of a quantity, like temperature, or weight. A vector has more than one number associated with it. A simple example is velocity. It has a magnitude, called speed, as well as a direction, like North or Southwest or 10 degrees west of North.
Describe how simple machines make use of conservation principles.
A simple machine uses a single applied force to do work against a single load force. Ignoring friction losses, the work done on the load is equal to the work done by the applied force. The machine can increase the amount of the output force, at the cost of a proportional decrease in the distance moved by the load. The ratio of the output to the applied force is called the mechanical advantage.
Be able to determine the magnitude of a vector, given its x- and y- components (the Pythagorean theorem is used here.]
A student drives his car 6.0 km, North before making a right hand turn and driving 6.0 km to the East. Finally, the student makes a left hand turn and travels another 2.0 km to the north. What is the magnitude of the overall displacement of the student? answer is 10 add 6 and 2 then square it and 6 and square root it
Identify force pairs and the forces that act on one another. [Remember, action/reaction pairs of forces can act on other masses.
According to Newton's third law, for every action force there is an equal (in size) and opposite (in direction) reaction force. Forces always come in pairs - known as "action-reaction force pairs." Identifying and describing action-reaction force pairs is a simple matter of identifying the two interacting objects and making two statements describing who is pushing on whom and in what direction. For example, consider the interaction between a baseball bat and a baseball
Determine the impulse delivered to an object.
An impulse is equal to the net force on the object times the time period over which this force is applied. Below, we derive impulse from the equation F = ma, which comes from Newton's second law of motion. Study the following three lines and read the commentary under them.
Describe why falling objects reach a terminal velocity.
As an object accelerates (usually downwards due to gravity), the drag force acting on the object increases causing acceleration to decrease. ... At this point the object ceases to accelerate together. And continues falling with a constant speed called terminal velocity.
Explain why "bouncing" is useful in many energy-capturing engines such as dams and water wheels.
Because it saves energy and adds extra speed
Given the moment of inertia of an object, use it to decide how much rotational energy an object can store, at the expense of kinetic energy.
http://hyperphysics.phy-astr.gsu.edu/hbase/rke.html
Relate how kinetic energy and potential energy are related in a particular problem.
http://www.bu.edu/gk12/kai/Lesson%204/E_Back.pdf
Determine the average force applied to an object over a given time interval.
F = m (vf - vi)/t F = force m = mass vavg = average velocity vf = final velocity vi = initial velocity t = time
Write out the rotational equivalents of linear properties such as position, velocity, momentum, energy, power, etc.
For simplicity, let's consider a uniform circular motion. For the length of the arc subtending angle " at the origin and "r" is the radius of the circle containing the position of the particle, we have s=rθ. Differentiating with respect to time, we have dsdt=drdtθ+rdθdt. Because drdt=0 for a uniform circular motion, we get v=ωr. Similarly, we also get a=αr where a stands for linear acceleration, while α refers to angular acceleration (In a more general case, the relationship between angular and linear quantities are given as v=ω×r, a=α×r+ω×v. ) Source: Boundless. "Relationship Between Linear and Rotational Quantitues." Boundless Physics Boundless, 26 May. 2016. Retrieved 18 Dec. 2016 from https://www.boundless.com/physics/textbooks/boundless-physics-textbook/rotational-kinematics-angular-momentum-and-energy-9/linear-and-rotational-quantities-89/relationship-between-linear-and-rotational-quantitues-333-7735/
State Newton's First Law of Motion and give examples of its use
Force is any influence that causes an object to change its shape or its state of motion. An unbalanced force is an external force that changes the state of motion of the object. Newton's first law of motion is also referred to as the law of inertia, where inertia is the resistance to change in motion. example:A fireman turns on his hose & is knocked backwards
Identify a system and its surroundings and explain how external forces affect a system.
If there is no net external force acting on the system then linear momentum is conserved. You can identify internal forces as they must occur in equal in magnitude but opposite in direction pairs - Newton's third law. So you find a force in the system f12f12 which is the force on part 11 of the system due to part 22 of the system which has its equal in magnitude opposite in direction twin, f21f21 force on part 22 of the system due to part 11 of the system. There is no such pairing of forces within the system for external forces which are forces on the system due to something outside the system so their Newton's third law pair would be a force on something outside the system due to force produced by system.
Determine the change in an object's potential energy, given suitable information.
PEgrav = mass • g • height
Determine the maximum height reached and the distance traveled before it hits the ground when a projectile is launched at a given angle and speed.
Projectiles can also be launched at an angle to the Earth's surface. When this occurs, the velocity in the vertical direction (viy) is no longer equal to zero. There is velocity in both the horizontal and vertical directions. And the shape of the trajectory will now include both sides of the parabola: as the projectile moves up and as it moves down. However, the analysis of the motion is virtually the same as before. The only thing that is different is we now need to determine the initial vertical and horizontal components of the initial velocity. To determine the horizontal and vertical components of the initial velocity we will use trigonometric identities: The diagram below shows the entire path of a projectile launched at an angle. We can see the velocity at certain points along the trajectory; as well as the corresponding horizontal and vertical components of the velocity. Notice that the horizontal component is of equal magnitude at any point along the trajectory. Again, because we are ignoring air resistance, there is no external force in the horizontal direction. So the horizontal component of velocity will remain equal at any point along the projectile's path. As always, due to gravity, the vertical component of velocity changes along its trajectory. Here are some of the special points to made note of: Initially the vertical component of velocity is large and acting in the upwards direction. As the projectile continues to move upwards, the vertical velocity decreases at a rate of 9.81 meters per second squared (acceleration due to gravity). When the projectile reaches the top of the trajectory (its maximum height), the vertical component of velocity is zero. At this point, the velocity is equal to the horizontal component of velocity. As the projectile moves downward, the vertical component of velocity increases in the downward direction; again, at a rate of 9.81 meters per second squared. Another feature to take note of is that the speed is equal at equal heights. The only difference is the direction.
Use Newton's law of universal gravitation to determine forces and accelerations between two bodies.
So as the mass of either object increases, the force of gravitational attraction between them also increases. ... Since gravitational force is inversely proportional to the square of the separation distance between the two interacting objects, more separation distance will result in weaker gravitational forces.
Distinguish between static and kinetic friction.
The Force of Static Friction keeps a stationary object at rest! Once the Force of Static Friction is overcome, the Force of Kinetic Friction is what slows down a moving object!
Estimate where the center of gravity of an object lies and use it to decide whether the object is in stable or unstable equilibrium. Describe why an object will tumble over if pushed.
The center of mass is the point where all of the mass of the object is concentrated. When an object is supported at its center of mass there is no net torque acting on the body and it will remain in static equilibrium. An easy way to determine the location of the center of mass of a rigid pole is to support the pole horizontally on one finger from each hand. Gently slide your fingers together. When your fingers meet, you will be at the center of mass at which time you can easily hold up the pole with only one finger as long as it can withstand the entire weight of the pole. Try it with a bat or a broom. If the object is uniform, for example a meter stick, the center of mass will be at the exact geometric center; if the object is irregular in shape the center of mass will be closer to the heavier end.
Determine the angular momentum of a rotating object, given suitable information, and use it, along with the concept of Conservation of Angular Momentum, to solve rotation problems.
The conserved quantity we are investigating is called angular momentum. The symbol for angular momentum is the letter L. Just as linear momentum is conserved when there is no net external forces, angular momentum is constant or conserved when the net torque is zero. We can see this by considering Newton's 2nd law for rotational motion: τ→=dL→dt, where τ is the torque. For the situation in which the net torque is zero, dL→dt=0. If the change in angular momentum ΔL is zero, then the angular momentum is constant; therefore, L→=constant (when net τ=0). This is an expression for the law of conservation of angular momentum.
Describe how the gravitational force between two objects depends on the masses and distances and how the force changes with mass and distance.
The force of gravity between two objects is determined by the mass of each object and the distance between their centers. Objects with a greater amount of mass will exert a greater degree of gravitational pull, but as the distance between two objects increases, the gravitational force between them lessens. The significance of distance with regard to large masses, such as planets, plays an important role in the science of Astronomy.
Explain why satellites can remain in circular orbit about a planet or moon without falling.
The fundamental principle to be understood concerning satellites is that a satellite is a projectile. That is to say, a satellite is an object upon which the only force is gravity. Once launched into orbit, the only force governing the motion of a satellite is the force of gravity. Newton was the first to theorize that a projectile launched with sufficient speed would actually orbit the earth. Consider a projectile launched horizontally from the top of the legendary Newton's Mountain - at a location high above the influence of air drag. As the projectile moves horizontally in a direction tangent to the earth, the force of gravity would pull it downward. And as mentioned in Lesson 3, if the launch speed was too small, it would eventually fall to earth. The diagram at the right resembles that found in Newton's original writings. Paths A and B illustrate the path of a projectile with insufficient launch speed for orbital motion. But if launched with sufficient speed, the projectile would fall towards the earth at the same rate that the earth curves. This would cause the projectile to stay the same height above the earth and to orbit in a circular path (such as path C). And at even greater launch speeds, a cannonball would once more orbit the earth, but now in an elliptical path (as in path D). At every point along its trajectory, a satellite is falling toward the earth. Yet because the earth curves, it never reaches the earth.
Determine v or r or ω of a rotating system, given suitable information.
The motion of a point on one tectonic plate relative to another plate can be described by the relative velocity vector v. The velocity v has magnitude and direction and is given by the cross product of the angular velocity vector ω and the plate rotation vector r: v = ω x r
State Kepler's law of planetary motion and use the 3rd Law to determine rotational periods, T, from a given radius of orbit, R, or vice versa.
The path of the planets about the sun is elliptical in shape, with the center of the sun being located at one focus. (The Law of Ellipses) An imaginary line drawn from the center of the sun to the center of the planet will sweep out equal areas in equal intervals of time. (The Law of Equal Areas) The ratio of the squares of the periods of any two planets is equal to the ratio of the cubes of their average distances from the sun. (The Law of Harmonies) http://www.physicsclassroom.com/class/circles/Lesson-4/Kepler-s-Three-Laws
Describe what is meant by a "pseudo force".
The physically apparent but nonexistent force needed by an observer in a noninertial frame to make Newton's laws of motion hold true. Centrifugal force is a pseudo force. Also called fictitious force.
Distinguish between elastic and inelastic collisions.
The primary difference between, elastic and inelastic collisions is, in elastic collision, kinetic energy is conserved and in inelastic collisions, kinetic energy is not conserved. But in both elastic and inelastic collisions, momentum is conserved.
Describe how friction affects motion and force on an object and calculate the frictional force, given suitable information.
The standard equation for determining the resistive force of friction when trying to move two objects or materials with respect to each other shows the relationship between the force of friction, the coefficient friction, and the normal force pushing the two objects together. This equation is written as Ff = μN where: Ff is the resistive force of friction μ is the coefficient of friction for the two surfaces (Greek letter "mu") N is the normal or perpendicular force pushing the two objects together μN is μ times N Ff and N are measured in units of force, which are pounds or newtons.
State Newton's Third Law of Motion and give an example of its use.
The statement means that in every interaction, there is a pair of forces acting on the two interacting objects. The size of the forces on the first object equals the size of the force on the second object. The direction of the force on the first object is opposite to the direction of the force on the second object. Forces always come in pairs - equal and opposite action-reaction force pairs. example: fish swimming
Determine the weight of an object, given its mass.
The weight of an object is the force of gravity on the object and may be defined as the mass times the acceleration of gravity, w = mg. Since the weight is a force, its SI unit is the newton. Density is mass/volume.
Perform a "free-fall" calculation under gravitational attraction.
There are a few conceptual characteristics of free fall motion that will be of value when using the equations to analyze free fall motion. These concepts are described as follows: An object in free fall experiences an acceleration of -9.8 m/s/s. (The - sign indicates a downward acceleration.) Whether explicitly stated or not, the value of the acceleration in the kinematic equations is -9.8 m/s/s for any freely falling object. If an object is merely dropped (as opposed to being thrown) from an elevated height, then the initial velocity of the object is 0 m/s. If an object is projected upwards in a perfectly vertical direction, then it will slow down as it rises upward. The instant at which it reaches the peak of its trajectory, its velocity is 0 m/s. This value can be used as one of the motion parameters in the kinematic equations; for example, the final velocity (vf) after traveling to the peak would be assigned a value of 0 m/s. If an object is projected upwards in a perfectly vertical direction, then the velocity at which it is projected is equal in magnitude and opposite in sign to the velocity that it has when it returns to the same height. That is, a ball projected vertically with an upward velocity of +30 m/s will have a downward velocity of -30 m/s when it returns to the same height. These four principles and the four kinematic equations can be combined to solve problems involving the motion of free falling objects. The two examples below illustrate application of free fall principles to kinematic problem-solving. In each example, the problem solving strategy that was introduced earlier in this lesson will be utilized.
Describe how and why tides rise and fall.
Tides refer to the rise and fall of our oceans' surfaces. It is caused by the attractive forces of the Moon and Sun's gravitational fields as well as the centrifugal force due to the Earth's spin. As the positions of these celestial bodies change, so do the surfaces' heights.
acceleration
Use the formula to find acceleration. First write down your equation and all of the given variables. The equation is a = Δv / Δt = (vf - vi)/(tf - ti). Subtract the initial velocity from the final velocity, then divide the result by the time interval.
Use the Work-Energy Theorem to solve a problem, given suitable information.
W net = mv f 2 - mv o 2 K = mv 2
Calculate the work done on an object and the power involved, given suitable information.
Work can be defined as transfer of energy. In physics we say that work is done on an object when you transfer energy to that object. If one object transfers (gives) energy to a second object, then the first object does work on the second object. Work is the application of a force over a distance. Lifting a weight from the ground and putting it on a shelf is a good example of work. The force is equal to the weight of the object, and the distance is equal to the height of the shelf (W= Fxd). Work-Energy Principle --The change in the kinetic energy of an object is equal to the net work done on the object.
Determine the angle, treating momenta as vectors, in which colliding bodies would move after collision.
http://www.physicsclassroom.com/calcpad/momentum
Interpret a graphical representation of motion and sketch a graph of motion, given suitable information.
constant velocity means constant slope negative slope equals negative velocity positive slope means positive acceleration and velocity
Determine the final velocity of bodies that have collided.
pi = m1vi1 one person isn't moving (m1 + m2)vf = m1vi1
Describe what is meant by "geosynchronous orbit" and what the requirement is of such an orbit in terms of trajectory.
rotates around the earth in a one day period becuase it is being pulled by the moon earth moon and sun so it keeps it going for a day to rotate around the earth
Define relevant terms such as action and reaction, vector components, impulse, elastic and inelastic collisions, etc
vector components- in physics, when you break a vector into its parts, those parts are called its components. For example, in the vector (4, 1), the x-axis (horizontal) component is 4, and the y-axis (vertical) component is 1 impulse- ince force is a vector quantity, impulse is also a vector in the same direction. Impulse applied to an object produces an equivalent vector change in its linear momentum, also in the same direction. The SI unit of impulse is the newton second (N. elastic- ) able to resume its normal shape spontaneously after contraction, dilatation, or distortion.
