Angular kinematics
What is the unit of frequency in rotational motion?
s^-1 or Hz
What is the unit of torque?
Newton meters
What is the equivalent of force in rotational motion?
Torque
In the following equation, what does x' stand for?
x' = x - vt
It is the position of event in second reference frame
In 1905, who came up with their own theory of special relativity?
Albert Einstein
How does the linear accelration at a radius r from the axis of rotation relate to the angular acceleration? (assume the object is in translational rest)
a=αr
In what angle to the tangent of a circle around the axis of rotation should a force be applied to maximize the torque?
0°
What is missing in the formula τ=Frθ?
A sine function affecting the angle θ
When is Galilean relativity used?
For velocities much smaller than the speed of light:
v << c
Does time dilate or contract?
Time dilates for the stationary observer.
What is the formula of kinematics (without looking at your booklet) which does not include acceleration and allows to predict motion in constantly angularly accelerating motion?
Δθ = (ωi+ωf)t/2
What information are you missing to calculate the total kinetic energy of a rolling object with a mass m, moment of inertia I, and linear velocity v?
the radius r
Is the following equation from Galilean or Special relativity?
u' = u - v
Galilean relativity.
It is the velocity addition equation
What stays the same regardless of its reference frame?
Bonus: state the equation.
Time is invariant for Galilean relativity.
Eq: t = to
What are the two postulates of special relativity?
The speed of light and laws of physics remain the same throughout the reference frames.
What is the frequency of rotation of an object accelerating at 1 radian per second squared, initially at rest after 2 seconds.
1/pi or 0.318 Hz
Calculate the rotational kinetic energy of a point mass of 2 kg spinning around an axis that is 2 m away, and that is spinning with an angular momentum of 6 kilograms metres squared per second.
2.25 J
Definition of inertial reference frame.
A reference frame that is NOT accelerating
What is a reference frame? [3 marks]
A set of coordinates to record the position and time of an event.
Is the space-time interval an invariant or variant property?
Invariant property.
Calculate the angular displacement after 2 seconds of an object angularly accelerating at 4 radians per second with an initial linear speed at a radius of 0.5 meters of 1 meter per second.
12 radians
Calculate the rotational kinetic energy of a ring of mass 0.02 kg, moment of inertia of 0.000002 kg m^2, and an linear speed at a point on the ring of 1 m s^-1
0.0001 J
Which is the correct equation for length contraction?
a) L=L0 / 𝛾
b) L=L0 ᐧ 𝛾
a) L=L0 / 𝛾
What remains constant in all inertial reference frames?
Newton's laws of motion are the same in all inertial reference frames
In the relativistic velocity addition equation , what does u' represent?
Velocity of X relative to Y