Circular Motion & Gravitation (topic 6)

Question 1

Linear speed equation

Answer 1

v = 2πr / T

where,

v = linear speed (ms^-1)
r = radius (m)
T = period (sec)

Question 2

Angular speed equation

Answer 2

ω = 2π / T OR ω = 2πf

where,

ω = angular speed (rad sec^-1)
T = period (sec)
f = frequency (Hz or sec^-1)

Question 3

Relation between linear speed and angular speed

Answer 3

v = ωr

where,

v = linear speed (ms^-1)
ω = angular speed (rad sec^-1)
r = radius (m)

Question 4

Centripetal acceleration equation

Answer 4

a = v^2 / r

where,

a = acceleration (ms^-2)
v = linear speed (ms^-1)
r = radius (m)

Question 5

Centripetal force equation

Answer 5

F = mv^2 / r OR F = mω^2r

where,

F = force (N)
m = mass (kg)
v = linear speed (ms^-1)
r = radius (m)
ω = angular speed (rad sec^-1)

Question 6

Field strength equation

Answer 6

F = G Mm / r^2

where,

F = force of attraction between two masses (N)
G = gravitational constant
M, m = mass (kg)
r = distance between center of both masses (m)

Question 7

Gravitational field strength

Answer 7

g = F / M OR g = G M/r^2

where,

g = gravitational field strength (N kg^-1)
F = force (N)
M = mass (kg)

Question 8

Orbital speed equation

Answer 8

V = √(GM / r)

where,

V = linear speed
G = gravitational constant
M = mass
r = orbital radius

Question 9

Kepler’s 3rd law

Answer 9

T^2 = 4π^2 / GM * r^3

Where,

T = time
G = constant
M = mass
r = radius

Question 10

Force exerted on mass by rod

Answer 10

• Is non zero
• Changes magnitude throughout rotation
• Is not always directed towards the center
• Is a minimum at the top