# Physics

 translational motion: distance, velocity, acceleration. time x = x0 + v0t + (1/2)at2 translational motion: velocity, acceleration and distance v2 = v02 + 2ax translational motion: velocity, acceleration and time v = v0 + at how does a projectile stay in motion? what keeps it in motion? inertia peak height of a projectile v0 = sin(0) - sq.rt.(2gh) horizontal distance traveled of a projectile x = vt . cos(0) peak velocity no velocity, but acceleration = 10 PE and KE of projectile object at its peak PE is maximizedKE is minimized (energy must be conserved) projectile path is independent of.... mass two objects launched with the same velocity will... hit the ground at the same moment what determines the time of flight? vertical velocity range of projectile is maximized at what angle from the horizontal? 450 symmetry of projectile says what? (speed wise) upward mirrors downward - initial speed = final speed air resistance is greater on (surface area, shape, and speed) larger surface areairregularly shapedgreater speed does mass affect force or path of air resistance force = no path = yes how does greater mass affect air resistance force is the same, so it decreases acceleration (F=ma) centripetal force (equation) F = m . v2/r inertia tendency of an object to stay in present state of motion (keeps projectile in motion) law of universal gravitation F = G(m1m2)/r2 friction points in what direction? always parallel to surface equation for torque t = F r sin0 if the board has mass, what do you do with torque? F=mg at center of board equation for work (not for gases) W = Fd cos0 what direction is friction (relative to work)? friction does negative work! work done lifting an object W = Fd = mg x h what is gravitational potential energy? work done by gravity: change PE = -W energy and power energy = work + heat so, P = (w + q)/s 1 revolution is equal to 2 pi r equation for angular momentum L = l x m x v l = lever arm, mv = linear momentum elastic collision mechanical energy is conserved inelastic collision mechanical energy is lost to internal energy (heat) perfect inelastic collision 2 objects stick together reverse inelasitc collisions (object dissipates into 2 sep. objects). In what direction do they travel opposite to each other ex: man standing on a board and jumps off what do you need to consider when determining their final positions? move in opposite directions consider their centers of gravity what is impulse? change in momentum Machine: inclined plane (how is work minimized?) straight up: W = ugh ramp: W = mg x sin x h What is theta equal to in the ramp height of ramp / distance of the ramp the greater the distance (d) the smaller the angle, the less work needed Machine: lever (torque) what does F need to equal to lift mass? F = mg in opposite direction How do you decrease the force required to life the object? increasing the lever arm (doubling lever arm, reduces force by a factor of 2) In a pulley, what is the tension in the rope? constant Tension = Force In a double pulley system, what is the force required to lift mass m? F = T T = 2mg F = (mg)/2 alpha decay 2 protons, 2 neutrons traveling of alpha particle not far stopped by skin, paper beta decay expulsion of an e- positron B+ is emitted (-1 atomic #) electron capture gain e- (-1 atomic number frequency of a gamma particle high frequency particle rest mass energy E = mc2 fussion combining 2 (?) from (?) combining 2 nuclei from a heavier nucleus fission splitting a single nucleus into 2 lighter nuclei where does energy for fusion and fission come from? mass defect density formula density = m/v density constant for gases and liquids? constant for liquids and solids change for gases, because they are compressible What is specific gravity? density of a substance compared to density of water so specific gravity of water is 1 formula for fluid pressure P = F/A Do fluids at rest have uniform density in a sealed container? yes What is the pressure experience by fluids at rest with uniform density? P = density x g x y y = depth of fluid Where is pressure greatest for a fluid at rest? greatest depth (P=pgy) What if you have many fluids layered in a sealed container? P = (pgy)1 + (pgy)2 + (pgy)3........... What is the pressure of a fluid at rest with uniform density in an open container add atmospheric pressure to density x g x y hydraulic lift (equation) pressure is transferred completely: F1/A1 = F2/A2 What is the velocity of a fluid flowing (if you don't know rate or area)? v = sq.rt (2gh) buoyant force upward force acting on a submerged object what is buoyant force equal to? (not equation) weight of fluid displaced by submerged object equation for buoyant force FB = (density of fluid) x (volume) x (g) floating object - submerged portion of object = density of object/density of fluid How much of an object will float in water if its specific gravity is 0.4? 60% does buoyant force change with depth? No What is the apparent mass on an object (when it is submerged)? mass of the fluid displaced thats why we weigh so little in water equation for fluid flow Q = (area)(volume) does fluid flow faster in a wider pipe, or a more narrow pipe? narrow ideal fluid flows at a constant rate K = Pressure + (density)(g)(h) + (1.2)(p)(v2) K is constant, specific to fluid in a flow surface tension and temperature increase temperature = weaker surface tension formula for stress force/area formula for strain change in dimension/original dimension what are stress and strain stress is done on an object strain is how the object responds modulus of elasticity stress/strain What is Coloumb's law? (equation) What does it mean? describes force between two charges F = k (q1q2) / r k = 9 x 109 Coloumb's law resembles what? But? gravitational force (G)(m1m2)/(r2) but, gravitational force is attractive electrical force is repulsive electric field - in what way are the lines drawn? What does the length of the line indicate? (+) ----------------> (-) length = strength (smaller is stronger) What is the electric field created by charge Q? E = k x (Q)/(r2) What is the force felt by charge q in the electric field E? F = E x q What makes and feels the field? Q makes the field q feels the field [F = k x (Qq)/(r2) What is the potential energy of of the charge in electric field? Potential energy (U) = force x displacement (like ugh) U = Eq x h How does potential energy change when moving perpendicular to electric field? doesn't change same way that moving parallel to surface of the earth doesn't change gravitational potential energy What is an electric dipole? created by 2 opposite charges with equal magnitude (+) and (-) fall/rise to lower/higher potential? + charge falls to a lower potential - charge rises to a higher potential high/low potential and +/- potenital high potential = + potentiallow potential = - potential How do we measure movement of a charge? current (A) So, what is current? (How is it measured) Coloumbs/second Current flows in what direction (relative to potential energy) current flows from high potential to low potential In what direction does current flow (relative to electron flow or electron velocity)? current moves in opposite direction of e- flow conducting electricity: what are good conductors and poor conductors? good = allow e- to flow freely [metals]poor = hold e- tightly in place [resistors] What is induction? charging a conductor circuit equations: current, voltage, resistance, capacitance V = IR I = Q/t C = Q/V what is capacitance? ability to store charge per unit voltage [Q/V] voltage is the same thing as...... and it depends on potential energy depends on distance plates that are further apart will have greater/less voltage and capacitance? greater voltage less capacitance What is a capacitor? temporarily stores energy in a circuit What is the separation of charges in a capacitor? emf between the plates what is resistance? resistance to flow of charge resistance is directly proportionate to what? length of wire [R = density x (length/area)] resistance and temperature resistance increases with temperature [thermal oscillations impede with flow] Kirchoff's Rules: - amount of current flowing in and out - voltage around the circuit -battery - amount of flow in = amount of flow out - votalge around any path in circuit must sum = 0 - battery adds energy to circuit How does battery add energy to the circuit? increases voltage from one point to another (emf = voltage added) Diaelectric constant (K) substance between plates of a capacitor -must be insulator to separate charge-resists creating EF, in order to store energy Resistors in series/parallel what is constant? series = add [current is constant] parallel = 1/R [voltage is constant] what is the terminal voltage? (equation) V = emf - IR AC Current - what's going on? e- don't move in one direction, they oscillate back and forth maximum current and maximum velocity in an AC Current Vmax = sqrt.(2) x Vmax Imax = sqrt.(2) x Imax What creates a magnetic field? charging electric field currents (moving charges) creates the magnetic field + and - of electric field corresponds to what in magnetic field? north and south north = + and south = - In what direction do magnetic lines point? north -------> south Doess a stronger magnetic field have closer lines, or further apart? closer lines = stronger fied How does the KE of a particle moving through the magnetic field change? no work done by the magnetic field, means no change in KE due to the magnetic field What is magnetic force? F = q x V x B x sin(0) force is applied in what direction relative to both velocity and magnetic field force is perpendicular to both velocity and magnetic field What is the work done by magnetic force? no work: because it's perpendicular to velocity What way does magnetic field act? like centripetal force (mv2/r) because charged particle moves in a circle What will move through a magnetic field with a smaller radius: a proton or an electron electron: because it has smaller mass [F = mv2/r] Right Hand Rule thumb = direction of current fingers = direction of magnetic field palm = direction of force What results from a change in magnetic field? an electrical field What happens to the mechanical energy in a magnetic field when it is changed and creates an electric field? mechanical energy to create the field is dissipated as heat What is the magnetic flux? number of magnetic fields running through the loop what does change in magnetic flux do? induces an emf What is a magnetic field generated by? a moving charge moving charge experiences what when moving through a magnetic field? force = qvBsin0 In what direction is this force? perpendicular to velocity and magnetic field (B) At equilibrium, in an electric and magnetic field, what is the net force acting on a particle? 0 force from electric field = force from magnetic field Eq = qvBsin(0) How can we find the acceleration or distance of a particle traveling through an electric or magnetic field F = ma set force (Eq) or (qvbsin) = mass x acceleration distance = (1/2)at2 Authornatalieplana ID79687 Card SetPhysics DescriptionPhysics Updated2011-04-19T12:35:20Z Show Answers