Week 2 Motion in 2D and 3D 2

Question 1

When is a polar coordinate system most useful

Answer 1

most useful when dealing with circular motion

Question 2

define the two components in a polar coordinate system

Answer 2

r - distance from origin axis to the point

θ - angle that the r vector makes with the axis

Question 3

give the 4 polar cartesian conversion equations

Answer 3

r = sqrt (x^2 + y^2)
θ = arctan(y/x)
x = rcosθ
y = rsinθ

Question 4

what is the velocity in polar coordinates equation

Answer 4

v = dr/dt x r^ + r x dθ/dt x θ^

Question 5

what can we say about the velocity when θ is constant

Answer 5

there is only a radial component of velocity

Question 6

what can we say about velocity when r is constant

Answer 6

there is only a tangential component of velocity

Question 7

what is an inertial frame

Answer 7

reference frame that moves with constant velocity

Question 8

what is relative velocity

Answer 8

velocity of an object as seen from the perspective of a particular observer

Question 9

give the two Galilean transformation equations for displacement and velocity

Answer 9

v = v' + u
r = r' + ut