Physics Answers

To immobilize a fractured femur (the thigh bone), doctors often utilize the Russell traction
system illustrated in the figure below. Notice that one force is applied directly to the knee,
F1, while two other forces, F2 and F3, are applied to the foot. The latter two forces combine
to give a force F2 + F3 that is transmitted through the lower leg to the knee. The result is that
the knee experiences the total force Ftotal = F1 + F2 + F3. The goal of this traction system is to
have Ftotal directly in line with the fractured femur, at an angle of 20.0° above the horizontal.
Find (a) the angle

Consider an isolated system, consisting of a box of volume V0 with a
partition which separates it into two subsystems; the first subsystem has
a volume of 0.4 V0 and contains one mole of an ideal gas at 300 K, while
the other is evacuated. Calculate the entropy change in the gas during
the process of its (free) expansion on removing the partition.

Consider an isolated system that contains two pieces of copper sepa-
rated by an (internal) insulating wall. Initially, the first piece is at 500K
and the second is at 300K. Calculate the entropy change in the sys-
tem when the insulating wall is removed; assume that each piece has
half a mole of copper in it. Given: Specific heat capacity of Cu is
CP = 22.6JK−1mol−1
. [Hint: S is an extensive state function].
(b) What is the entropy change of the universe ? Comment whether the
process is reversible/irreversible ?
(c) Repeat your calculations for a molar heat capacity which is a function
of T: CP = 22.6 + 6.28e − 03 T Jmol−1 K−1
. How does the equilibrium T
change for such a CP ? Can you justify it ?

Suppose, you have a block of Cu of the size 1 mole. It is initially at 300 K
and is brought to a temperature of 400 K over 2 steps where temperature is
first brought to T = 350 K and then to 400K by contact with appropriate
thermal reservoirs. Treat the combination of the Cu block and the thermal
reservoir at every step to be an isolated system. Compute ∆S for the
process and compare your results with that of the previous problem. Can
you comment on the results.

A sports car as rigid body needs to make a record jump from acertain ramp with some specific height covering certain horizontal distance.

Expectation valu of (momentum)^4 in one dim linear harmonic oscilator

Two pulleys with masses m1 = 1 (kg) and m2 = 2 (kg) fixed
coaxially to each other are fixed on the wall so that they can rotate around point O (bigger pulley has 2r and the small one on the inside of the big one has radius r). Mass m3 = 3 (kg) is connected to the rope wound on a reel with radius r = 1 (m). Initially a constant force of

What is the boundary condition for normalized wave function

A wave function is given to be