Review. You are standing on the ground at the origin of a coordinate system. An airplane flies over you with constant velocity parallel to the x axis and at a fixed height of 7.60 × 10 3 m. At time t = 0, the airplane is directly above you so that the vector leading from you to it is P → 0 = 7.60 × 10 3 m . At t = 30.0 s, the position vector leading from you to the airplane is P → 30 = ( 8.04 × 10 3 i ^ + 7.60 × 10 3 j ^ ) m as suggested in Figure P3.31. Determine the magnitude and orientation of the airplane’s position vector at t = 45.0 s. Figure P3.31
Review. You are standing on the ground at the origin of a coordinate system. An airplane flies over you with constant velocity parallel to the x axis and at a fixed height of 7.60 × 10 3 m. At time t = 0, the airplane is directly above you so that the vector leading from you to it is P → 0 = 7.60 × 10 3 m . At t = 30.0 s, the position vector leading from you to the airplane is P → 30 = ( 8.04 × 10 3 i ^ + 7.60 × 10 3 j ^ ) m as suggested in Figure P3.31. Determine the magnitude and orientation of the airplane’s position vector at t = 45.0 s. Figure P3.31
Review. You are standing on the ground at the origin of a coordinate system. An airplane flies over you with constant velocity parallel to the x axis and at a fixed height of 7.60 × 103 m. At time t = 0, the airplane is directly above you so that the vector leading from you to it is
P
→
0
=
7.60
×
10
3
m
. At t = 30.0 s, the position vector leading from you to the airplane is
P
→
30
=
(
8.04
×
10
3
i
^
+
7.60
×
10
3
j
^
)
m
as suggested in Figure P3.31. Determine the magnitude and orientation of the airplane’s position vector at t = 45.0 s.
An aluminum rod and a copper rod have the same length of 100cm at 5C. At what temperatures would one of the rods be 0.5 mm longer than the other? Which rod is longer at such temperature?
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…
Chapter 3 Solutions
Physics for Scientists and Engineers, Technology Update, Hybrid Edition (with Enhanced WebAssign Multi-Term LOE Printed Access Card for Physics)
Microbiology with Diseases by Body System (5th Edition)
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