# znotes Flashcards

1
Q

A

One radian is the angle subtended from the center of the circle by an arc length equal to the radius of the circle

2
Q

Angular displacement

A

The angle through which an object has moved through a circle

3
Q

Angular velocity

A

The rate of change of the angular position of an object as it moves along a curved path

ω= θ / t
ω= 2π / T = 2πf

4
Q

Linear velocity

A

v = ωr

5
Q

Centripetal force

A

Resultant force acting on an object perpendicular to its linear velocity towards the center of the circle. Causes circular motion.

F= mv^2 / r = mrω^2

6
Q

Centripetal acceleration

A

Derived by equating Newton’s 2nd law and centripetal force

```ma = mrω^2
a = rω^2 = v^2/r```
7
Q

Gravitational field strength

A

The force experienced per unit mass at a point in the gravitational field

g= GM/r^2

8
Q

Newton’s law of gravitation

A

The gravitational force present between two masses is directly proportional to the product of the two masses and inversely proportional to the square of their separation.

F = GMm/r^2

9
Q

Gravitational potential

A

The work done per unit mass in bringing a point mass from infinity to a point in the gravitational field

ϕ = −GM/r

Gravitational potential is negative because its maximum value is 0 at infinite distance away from the mass

gpe = mgh can be used on Earth’s surface

10
Q

Gravitational potential energy

A

The work done in bringing a point mass from infinity to a point in the gravitational field

U = mϕ = −GMm/r

11
Q

Centripetal acceleration

A

For an orbiting satellite the cnetripetal force is provided by the gravitational field

```GMm/r^2 = mv^2/r
v^2 = GM / r```
12
Q

Geostationary orbit

A

It is always above a fixed point on the equator of the Earth
Fixed period of 24hrs
Moves from West to East - same direction as Earth

13
Q

Escape velocity of a satellite

A

Initial KE + Initial GPE = 0
1/2mv^2 = GMm/r
v = (2GM/r)^ 1/2

14
Q

A

Number of molecules present in 12g of carbon-12

15
Q

Ideal gas

A

A gas which obeys the ideal gas equation for all temperatures, pressures and volumes.

pV = nRT
where R = 8.31

16
Q

Kinetic theory of gases

A

Negligible intermolecular forces of attraction
Volume of particles negligible to the volume of space between them
Collisions between particles are perfectly elastic
Time for collisions negligible between the time between collisions
Average kinetic energy is proportional to the temperature

17
Q

Mean square velocity < c >^2

A

Mean value of the square of the velocities of the molecules

18
Q

Molecular movement and pressure

A
```pV = 1/3 Nm< c >^2
pV = 1/3 nMr< c >^2```
19
Q

Kinetic energy of a molecule

A

K.E. = 1/2 m< c >^2

derived by equating two formulae in pV

3/2 kT = Ek

Therefore kinetic energy of particles is directly proportional to the temperature.

20
Q

Thermal equilibrium

A

When two or more objects in contact have the same temperature so there is no net flow of energy between them

21
Q

Absolute zero

A

Temperature at which a system has minimum internal energy