5th Six Weeks

Question 1

Uniform Circular Motion equations

Answer 1

Period: T = time/$=# of cycles; s
Frequency: f = # of cycles/time; Hz
Tangential Velocity/Linear Speed: Vt = (2pir)/T; m/s
Rotational Speed: w = Vt/r; rad/s (only when Vt is in m/s)
(rad/s)(1 rev/2pi rad) = rev/s
(rev/s)(360 degrees/1 rev) = degrees/s
Centripetal Acceleration: Ac = (Vt^2)/r; m/s^2
Centripetal Force: Fc = mAc; (m4pi^2r)/T^2; N
Acceleration: a = Fnet/m

m: mass
r: radius

Question 2

Momentum equations

Answer 2

p = m*v

p: momentum (kg m/s, direction)
m: mass
v: velocity

J = F*t

J: impulse (NS)
F: force
t: time

J = Ft = mdelta v = m(vnot - v) = delta p = pnot - p

not: initial
Delta: change

Question 3

Collision equations

Answer 3

Little capitalized F big lowercased t/Big capitalized F little lowercased t: change in momentum

pBefore Collision = pAfter Collision: m1v1+m2v2 = m1v1’+m2v2’

m: mass
v: velocity
‘: prime (new)

Question 4

Heat equations

Answer 4

Q = mcdelta t

Q: heat gain or loss; in calories, Joules; depends on mass
m: mass; in grams, kilograms
c: specific heat capacity; in J/g degrees C, cal/g degrees C, J/kg degrees C
delta t: change in temperature; in degrees C, K

Question 5

1st Law of Thermodynamics

Answer 5

Also known as Law of Conservation of Energy, this states that energy cannot be created or destroyed in an isolated system.

Question 6

2nd Law of Thermodynamics

Answer 6

This states that the entropy of any isolated system always increases.

Question 7

3rd Law of Thermodynamics

Answer 7

This states that the entropy of a system approaches a constant value as the temperature approaches absolute zero.

Question 8

Zeroeth Law

Answer 8

If two bodies are each in thermal equilibrium with some third body, then they are also in equilibrium with each other.

Question 9

Specific heat capacity

Answer 9

the heat required to raise the temperature of the unit mass of a given substance by a given amount (usually one degree)

Water: 4.18 J/g degrees C = 1 calorie

Question 10

Momentum

Answer 10

Refers to the quantity of motion that an object has; “mass in motion”; directly proportional to an object’s mass/velocity; vector quantity: both magnitude and direction; standard metric unit: kgm/s; kgmi/hr, kgkm/hr, gcm/s
Momentum is zero when the object is at rest.
A change in one of the variables might affect the momentum. If the change in momentum occurs over a short time, the force of impact is big. If it’s a long time, the impact is small.
The law of conservation of momentum states that in the absence of an external force, the momentum of a system remains unchanged.
A doubling of the mass results in a doubling of the momentum

Question 11

The Effect of Collision Time Upon the Force

Answer 11

• Force and time are inversely proportional.
• An object with 100 units of momentum must experience 100 units of impulse in order to be brought to a stop.
• The greater the time over which the collision occurs, the smaller the force acting upon the object. To maximize the effect of the force on an object involved in a collision, the time must be decreased

Question 12

Calibration

Answer 12

placement of divisions or marks on a measuring tool to allow it to accurately measure in accordance with known standards

Question 13

Centrigrade thermometer

Answer 13

the thermometer calibration process

Question 14

Conduction

Answer 14

the transfer of energy within materials and between different materials that are in direct contact

Question 15

Convection

Answer 15

heat is transferred by movement of the hotter substance from one place to another; hot water goes up, cold water sinks

Question 16

Radiation

Answer 16

Heat is transferred in the form of radiant energy, or electromagnetic waves; the emission of energy as electromagnetic waves or as moving subatomic particles, esp., high energy particles that cause ionization

Question 17

Longest to shortest waves

Answer 17

1. radio
2. microwave
3. infrared
4. visible
5. ultraviolet
6. X-rays
7. gamma

Question 18

Uniform circular motion

Answer 18

This is the motion of an object in a circle at a constant speed. It is constantly changing direction, and the object moves tangent to the circle. The direction of the velocity vector is the same (tangent) as the direction of the object’s motion, and the direction of the acceleration is inwards. The net force acting upon such an object is directed towards the center of the circle.

1. rotation: turns about an internal axis (24 hours)
2. revolution: turns about an external axis (365 days)

Question 19

Temperature

Answer 19

The degree of hotness or coldness of a body, object, or substance with reference to some standard value; measured in Celsius, Fahrenheit, Kelvin (has no degrees)

degrees C = (degrees F - 32 degrees) / 1.8
degrees F = 1.8 * degrees C +32 degrees

0 K = -273.15 degrees C
degrees C = K - 273.15 degrees C
K = degrees C + 273.15

zero point on Kelvin: absolute scale; lowest temperature that can be achieved

The volume and the pressure of a gas seem to reduce to 0 at a very specific temperature (assuming the gas remains as a gas)

Question 20

Convection current

Answer 20

a current in a fluid that results from convection

Question 21

Heat energy is transferred from one substance to another by:

The amount of heat transferred can be determined by

Answer 21

a. temperature difference

b. measuring the temperature change of a known mass of a substance

Question 22

Rebounding

Answer 22

bouncing off each other; involves a change in the direction of an object; the before-and-after collision is different