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# Phys-gen. questions

Question | Answer |
---|---|

when an object is in projectile motion and it reaches its maximum height, what happens to its vertical velocity | it is zero |

in projectile motion, how does the amount of time that an object takes to get to its max height compare to the amount of time that it takes for the object to fall back down? | it is equal to it |

can forces exist between objects that aren't touching? | yes |

is measurement of mass dependent on gravity? | no |

the weight of an object can be thought of as being applied at... | the center of gravity |

the center of gravity can only be located at an objects geometric center if it is... | a homogeneous body |

when does gravity decrease? increase? | farther away from the earth; closer to the earth |

what is Newton's first law? | F=ma=0 ; a body either at rest of in motion with constant velocity will remain that way unless a net force acts upon it |

Newton's first law is also known as... | the first law of inertia |

if there is no acceleration then there is no net... | force acting on the object |

what is Newton's second law? | ΣF=ma ; no acceleration of an object with mass, m, will occur when the vector sum of the forces results in a cancellation of those forces |

what is Newton's third law? | Fb=-Fa ; for every force exerted by object b on object a, there is an equal but opposite force exerted by object a on object b |

when solving problems that are not only in the x or y direction what do you need to do? | break it into its x and y components |

what is the weakest of the four forces known to us? | gravity |

what is the fixed pivot point in rotational motion known as? | fulcrum |

what generates rotational motion? | torque |

in circular motion, upon completion of one cycle what is the displacement of the object? | zero |

in circular motion that demonstrates a constant speed at all points along the pathway what direction does the velocity vector point? | tangent to the circular path |

in uniform circular motion, what is the tangential force equal to? | zero |

what generates centripetal acceleration? | centripetal force |

in circular motion, when a centripetal force is no longer acting on the object what path will the object take? | a path tangential to the circle at that point |

in nonuniform circular motion there is a ____ force acting to create a _____ acceleration | tangential |

in nonuniform circular motion, does the resultant force point towards the center of the circle? | no |

what governs the degree of static friction? | total area of contact |

does kinetic friction depend on the contact surface area or the velocity of the sliding object? | no, it is always a constant value |

which is larger: the coefficient of static friction or the coefficient of kinetic friction? | the coefficient of static friction |

an object experiencing translational equilibrium will have a constant ___ and __ | speed and direction |

torque is greatest when the force applied is in what direction? | perpendicular to the lever arm |

translational equilibrium is also known as what? rotational equilibrium? | first condition of equilibrium. second condition of equilibrium. |

are torques that generate clockwise rotation conventionally negative or positive? | negative |

in uniform circular motion, in what direction do the centripetal force and acceleration vector point? | directly to the center of the circular pathway |

what makes up the total mechanical energy? | the sum of an object's potential and kinetic energies |

what does the first law of thermodynamics state? | energy is never created or destroyed |

when will the sum of kinetic and potential energies be constant? | in the absence of nonconservative forces |

what are two things that determine a force as being conservative? | if the net work done to move a particle in a round trip path is zero OR if the net work done to move a particle between two points is the same regardless of the path taken |

the change in total mechanical energy of a system is equal to what? | the work done by nonconservative forces only |

what two ways can energy be transferred? | work and heat |

momentum of a system will be constant when? | in the absence of external forces |

is momentum conserved in an idealized collision? | yes |

what three types of collision conserve total momentum? | completely elastic collisions, inelastic collisions, and completely inelastic collisions |

what is conserved in a completely elastic collision | total momentum and total kinetic energy |

do inelastic collisions conserve kinetic energy? | no |

which kinetic energy (final or initial) is larger for an inelastic collision? | initial |

is kinetic energy conserved in completely inelastic collisions? | no |

how do inclined planes pulleys and levers make work easier? | by allowing for masses to be displaced through the application of lower force over a greater distance |

with an idealized pulley, how does the work put into the system compare to the work that comes out of the system? | equal |

the center of gravity and the center of mass will be the same point as long as what is held constant? | g |

what does the second law of thermodynamics state? | the entropy of the universy is always increasing except at absolute zero |

what does the third law of thermodynamics state? | absolute zero can never actually be reached |

what doesn't happen between objects in thermal equilibrium? | heat flow |

temperature is related to the average what of the particles? | motional kinetic energy |

are there negative temperatures on the Kelvin scale? | no |

a change of 1 degree on the Celsius scale is equal to a change of what on the Kelvin scale? | 1 unit |

is work done by a system positive or negative? | positive |

is heat flow into a system positive or negative? | positive |

is energy conserved even when friction is present? | yes |

objects in thermal contact and not in thermal equilibrium will ___ until ___ | exchange heat energy until they are in thermal equilibrium |

what are 2 different units for measuring heat besides the SI unit? | calorie and British thermal unit |

what are the best heat conductors? the poorest? | metals; gases |

what can all transfer heat by convection? | only fluids |

what is special about radiation? | it can travel through a vacuum |

what is the specific heat of water? | 1 Calorie |

what happens when heat is added or removed from a system undergoing a phase change? | nothing |

when will the temperature of an object in a phase change begin to change when heat is being added or removed from it? | when all of the substance has been converted to one phase |

are phase changes related to changes in kinetic or potential energy? | potential |

in graphing thermodynamic processes, what axes do volume, pressure and temperature go on? | volume on x, temperature on y, pressure on y |

how do you find the work done on a system by a pressure-volume curve? | area under the curve |

what happens to entropy when energy is distributed into a system? | it increases |

how likely is the spontaneous concentration of energy? | highly unlikely |

are any real processes reversible? | no |

what are three temperature dependent physical properties of materials? | length, volume, and conductivity |

what are considered fluids? | gases and liquids |

only solids can withstand what? | shear tangential forces |

2 units for density besides the SI unit? | g/ml g/cm^3 |

what is the density of pure water? | 1,000 kg/m^3 |

for an object to be more dense than water what must its specific gravity be? | greater than one |

pascal to atm to torr to 760 mmHg? | 1.013x10^5=1=760=760 |

are gases compressible? | yes |

is the buoyant force due to the liquid or the object? | the liquid |

what does surface tension result from? | cohesion |

cohesion occurs between molecules with what? | the same properties |

when will a meniscus form? | when adhesive forces are greater than cohesive forces |

when will a backwards meniscus form? | when cohesive forces are greater than adhesive forces |

when there is an indentation (such as due to an insects foot) on the surface of water, what leads to a net upward force? | cohesion |

what can be thought of as a measure of fluid friction? | viscosity |

what should you assume in low viscosity fluids with laminar flow? | conservation of energy |

what causes the formation of eddies? | turbulent flow |

do the layers in laminar flow have the same linear velocity? | no |

when the critical velocity for a fluid is exceeded, where does laminar flow occur? | only in the boundary layer |

how will a velocity vector point in relation to a streamline? | tangential |

what is constant for a closed system and is independent of changes in cross-sectional area | volumetric rate of flow |

how does a system at higher pressures density compare to one at a lower pressure? | greater |

for an incompressible fluid that is not experiencing friction forces, what sum will be constant for a closed container? | the sum of the static pressure and dynamic pressure |

an increase in the velocity of a fluid does what to the pressure that the fluid exerts on the walls? | decrease |

youngs modulus is applicable for what kind of forces? | stretching or pushing forces |

shear modulus is applicable for what kind of force? | parallel |

rank the bulk moduli of the three phases from smallest to largest | gases < liquids < solids |

the speed of sound is proportional to the square root of what modulus? | bulk modulus |

for all three moduli, what represents a more rigid material? | large |

incompressible fluids demonstrate an inverse relationship between what and what? | dynamic pressure and static pressure |

both fluids and solids can exert what? | perpendicular forces |

is an electrostatic force attractive or repulsive? | can be both |

lower humidity and cold air does what to charge? | it makes it easier for charge to become and remain separated |

what is the fundamental unit of charge and how many coulombs does it equal? | e=1.60x10^-19 C |

what is the direction of an electric field vector? | the direction that a positive test charge would move in the presence of the source charge |

do field lines or stream lines ever cross each other? | no |

what tells whether the force vector will be in the same direction of the electric field vector or not? | the sign on the charge |

if left to its own accord, in what direction will a charge move? | in a direction to decrease the system's electrical potential energy |

potential difference is also known as | voltage |

is electrostatic force conservative or nonconservative? | conservative |

in what direction does positive charge move spontaneously? | high voltage to low voltage |

is work done when moving a test charge from one point to another on an equipotential line? | no |

dipoles can be either ___ or ___ | transient or permanent |

the electric potential at any point along the plane of the perpendicular bisector of the dipole is what? | zero |

electric field vectors along the perpendicular bisector will point in a direction opposite to what? | a dipole moment |

when an electric dipole is placed in a uniform electric field, what will happen to it? | it will begin to rotate until it aligns itself with the electric field |

does an electric dipole placed in a uniform electric field experience translational motion? | no |