Try the following experiment away from traffic: where you can do it Safely. With the car VOU are driving moving slowly on a Straight, level road, shift the transmission into neutral and let the car coast. At the moment the car comes to a complete slop, step hard on the ln.ike and notice what you feel. Now repeal I he same experiment on a fairly gentle, uphill slope. Explain the difference in what a pet son tiding in the car feels in the two cases. (Brian Popp suggested the idea for this question.)
Try the following experiment away from traffic: where you can do it Safely. With the car VOU are driving moving slowly on a Straight, level road, shift the transmission into neutral and let the car coast. At the moment the car comes to a complete slop, step hard on the ln.ike and notice what you feel. Now repeal I he same experiment on a fairly gentle, uphill slope. Explain the difference in what a pet son tiding in the car feels in the two cases. (Brian Popp suggested the idea for this question.)
Solution Summary: The author explains that the acceleration is zero at the zero speed on the level road and the uphill slope the car is moving with a downhill acceleration.
Try the following experiment away from traffic: where you can do it Safely. With the car VOU are driving moving slowly on a Straight, level road, shift the transmission into neutral and let the car coast. At the moment the car comes to a complete slop, step hard on the ln.ike and notice what you feel. Now repeal I he same experiment on a fairly gentle, uphill slope. Explain the difference in what a pet son tiding in the car feels in the two cases. (Brian Popp suggested the idea for this question.)
ROTATIONAL DYNAMICS
Question 01
A solid circular cylinder and a solid spherical ball of the same mass and radius are rolling
together down the same inclined. Calculate the ratio of their kinetic energy. Assume pure
rolling motion Question 02
A sphere and cylinder of the same mass and radius start from ret at the same point and more
down the same plane inclined at 30° to the horizontal
Which body gets the bottom first and what is its acceleration
b) What angle of inclination of the plane is needed to give the slower body the same
acceleration
Question 03
i)
Define the angular velocity of a rotating body and give its SI unit
A car wheel has its angular velocity changing from 2rads to 30 rads
seconds. If the radius of the wheel is 400mm. calculate
ii)
The angular acceleration
iii)
The tangential linear acceleration of a point on the rim of the wheel
Question 04
in 20
Question B3
Consider the following FLRW spacetime:
t2
ds² = -dt² +
(dx²
+ dy²+ dz²),
t2
where t is a constant.
a)
State whether this universe is spatially open, closed or flat.
[2 marks]
b) Determine the Hubble factor H(t), and represent it in a (roughly drawn) plot as a function
of time t, starting at t = 0.
[3 marks]
c) Taking galaxy A to be located at (x, y, z) = (0,0,0), determine the proper distance to galaxy
B located at (x, y, z) = (L, 0, 0). Determine the recessional velocity of galaxy B with respect
to galaxy A.
d) The Friedmann equations are
2
k
8πG
а
4πG
+
a²
(p+3p).
3
a
3
[5 marks]
Use these equations to determine the energy density p(t) and the pressure p(t) for the
FLRW spacetime specified at the top of the page.
[5 marks]
e) Given the result of question B3.d, state whether the FLRW universe in question is (i)
radiation-dominated, (ii) matter-dominated, (iii) cosmological-constant-dominated, or (iv)
none of the previous. Justify your answer.
f)
[5 marks]
A conformally…
SECTION B
Answer ONLY TWO questions in Section B
[Expect to use one single-sided A4 page for each Section-B sub question.]
Question B1
Consider the line element
where w is a constant.
ds²=-dt²+e2wt dx²,
a) Determine the components of the metric and of the inverse metric.
[2 marks]
b) Determine the Christoffel symbols. [See the Appendix of this document.]
[10 marks]
c)
Write down the geodesic equations.
[5 marks]
d) Show that e2wt it is a constant of geodesic motion.
[4 marks]
e)
Solve the geodesic equations for null geodesics.
[4 marks]
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