MIDTERMS Flashcards
It is a description of how an object moves.
Kinematics
Who discovered that motion is determined by forces?
Galileo and Newton
In the absence of a net force, an object is at ______ or moves with _______.
rest, constant velocity
What model do we use for objects on which the net force is zero?
Mechanical Equilibrium Model
A particle at rest is in equilibrium. True or False?
True
A particle moving in a _________ at constant velocity is also in ________.
straight line, equilibrium
Mathematically: a vector = 0 vector; thus Newton’s second law equation is:
Fnet = sigma Fi = 0 vector.
What is the limitation of Mechanical Equilibrium Model?
Model fails if the forces aren’t balanced.
Newton’s laws are scalar equations. True or False?
False. vector equation
In Newtonian mechanics, what is the formula for acceleration?
a = Fnet / m. The forces acting on an object determine its acceleration.
What will happen if the forces acting on object are constant?
The object moves in constant acceleration.
In constant force model, the particle accelerates in the direction of the net force. Define it mathematically.
Fnet = sigmaFi =ma
What is the limitation of constant force model?
The model fails if the forces aren’t constant.
It is an intrinsic property of an object.
Mass
An attractive, long-range force between any two objects.
Gravity
In gravity, forces are equal on magnitude but opposite in direction. True or False?
True
Newton’s Law of Gravity equation:
F_1on2 or F_2on1 = Gm1m2 / r²
What is the value of G, called the gravitational constant?
6.67x10-¹¹ N m2/kg2
Give one of the basic constants of nature.
gravitational constant
Gravity is a constant force. True or False?
False. The force gets weaker as the distance between the object increases.
gravitational force formula:
FG = GM / R²
wherein;
M is basically (m1)(m2)
The direction of the gravitational force defines what we mean by ______.
“straight down”
All objects, regardless of mass, have the same free-fall ________.
acceleration
What is the average radius of the Earth?
6.37x10⁶ m
What is the mass of the earth?
5.98x10²⁴ kg
What would be the free-fall acceleration on a stationary earth?
9.83m/s²
It is a measurement, the result of “weighing” an object.
Weight
Since F_sp is a force, weight is measured in what?
Newtons
F_net=0 only if the upward spring force exactly balances the downward ________ of magnitude mg.
gravitational force
Having no sensation of weight.
Weightlessness
Defined as the force of an object that keeps it from slipping.
Static Force
An object remains at rest as long as f_s < fs max and slips when f_s = f_smax. True or False?
True
The direction of f_k is always opposite to the direction in which an object slides across the surface. True or False?
True
Kinetic friction is proportional to the magnitude of the normal force. f_k =μ_k n where, μ k is called the?
coefficient of kinetic friction
A wheel rolling on a surface also experiences friction, but not kinetic friction. What do you call this friction?
Rolling Friction
n=
mg
The ______ force is opposite in direction to v.
Drag
formula for the density (r) of the air
1.3kg/m³
Drag increases as v ______.
increases
Drag force ______ as an object falls and gains ______.
increases, speed
Refers to how forces cause circular motion.
Dynamics
What is the force that is always directed toward the same point?
Central force
What do you call a closed trajectory around a planet or star?
Orbit
The “force” that seems to push an object to the outside of a circle is commonly known as the ________.
Centrifugal force
What do you call the speed at which n=0?
critical speed (v_c)
Circular motion with a changing speed is called _______.
Nonuniform circular motion.
It is a measure of how “hot” or “cold” a system is.
Temperature
It is related to a system’s thermal energy.
Temperature T
It is defined as the kinetic and potential energy of the atoms and molecules in a system as they vibrate (solid) or move around (gas).
Thermal Energy
A system has more thermal energy when it is _______ than when it is _____.
hot, cold
A tool used to measure the temperature of a system.
Thermometer
In thermometer, the object’s temperature is determined by the ______ of the column of liquid.
length
It can be any small macroscopic system that undergoes a measurable change as it exchanges thermal energy with its surroundings.
A thermometer
What does a thermometer needs to be a useful measuring device?
Temperature scale
Who sealed mercury in a small capillary tube and observed how it moved up and down the tube as the temperature changed?
Anders Celsius
Anders Celsius is credited with inventing the ________ scale.
Celsius
Formula for fahrenheit scale:
T_f = (9/5)(C) + 32
What can be used as a thermometer?
Any physical property that changes with temperature.
A useful thermometer has a physical property that changes linearly with temperature. True or False?
True
What is one of the most important scientific thermometers?
constant-volume gas thermometer
What relationship does temperature and pressure has?
Linear relationship
Are all gas extrapolate to zero pressure? Yes or No?
Yes, at the same temperature: T_0 = -273°C
It is due to the collisions of the molecules with each other and the walls of the container.
Pressure in a gas
What would it mean if the pressure is zero?
All motion had ceased. If there were no motion, system’s thermal energy would be zero.
What is the lowest temperature that has physical meaning?
absolute zero
The SI absolute temperature having the same unit size as the Celsius scale is called ______.
Kelvin scale
Formula for Celsius to Kelvin:
T_K = T_C + 273
A temperature scale with the zero point at absolute zero is called an.
absolute temperature scale
If the temperature is measured on an absolute scale will have T>0. True or False?
True
What is the temperature scale having the same unit size with Kelvin scale?
Celsius scale
What is the unit of Kelvin?
Simply kelvins, not degrees Kelvin
It is the reason why the liquid rises in a thermometer and why pipes, highways, and bridges have expansion joints.
Thermal Expansion
What is the symbol for the material’s coefficient of linear expansion?
a (Greek alpha)
For most solids, the _______ in length, ∆L/L, is proportional to the temperature change (∆T).
fractional change
What metal alloy that is specifically designed to have extremely low thermal expansion?
Invar
What is the unit of fractional change?
per degree Celsius
If an object’s volume changes during a temperature change, the fractional change in volume is:
∆V/V = B∆T (greek B)
What is the B(Greek beta) in the fractional change in volume?
coefficient of volume expansion
Liquids are characterized by a volume-expansion coefficient but not by a linear-expansion coefficient. Why?
Because liquids are constrained by the shape of their container.
The volume of water contracts when the temperature is lowered, but not until it reaches __C.
4°C
Water has a maximum density at what temperature?
4°C
It is an energy of the system due to the motion of its atoms and molecules and the stretching/compressing of spring-like molecular bonds.
Thermal Energy
Does the system’s thermal energy exist even if the system is isolated thermally with its environment?
Yes
Refers to the energy transferred between the system and the environment as they interact.
Heat
HEAT IS NOT A PARTICULAR FORM OF ENERGY!!!!
Okay
Heat may cause the system’s thermal energy to change does that make the heat and thermal energy the same?
No. Heat is not a form of energy while thermal energy is.
It is a state variable that quantifies the hotness or coldness of a system.
Temperature
Temperature is related to the thermal energy per molecule. True or False?
True
What is the symbol for specific heat?
c
What is the specific heat of water?
4190J/kg K
A measure of the AVERAGE kinetic energy of the individual particles of substance.
Temperature
It is the TOTAL energy of ALL of the particles.
Thermal Energy
It refers to the thermal energy moving from a warmer object to a cooler object, trying to reach to reach thermodynamic equilibrium.
Heat
The amount of energy that raises the temperature of 1kg of a substance by 1 K.
Specific Heat
What is the specific heat of gold?
129J/kg K
What does uppercase M symbolizes?
Mass of an entire system
What happens to the metals with small specific heat?
They warm up or cool down quickly. (that is why it takes time for water to cool down because it has a very large specific heat).
It is the amount of energy that raises the temperature of 1 mol of a substance by 1 K.
molar specific heat (C) *uppercased
Formula for molar specific heat:
Q = nC∆T
Most elemental solids have C ≈ 25J/mol K. True or False?
True
What is heat according to Antoine Laviosier?
Heat is a fluid like substance called caloric.
What do you call the parameters used to characterized or describe a macroscopic system?
State Variables
