Molecular Physics | Thermodynamics Answers

A block of mass m₁ = 20.4 kg is on a frictionless table to the left of the second block of mass m₂ = 23.7 kg, attached by a horizontal string (see the figure below).

(a) If a horizontal force of 1.13 ✕ 10² N is exerted on the block m₂ in the positive x-direction, use the system approach to find the acceleration (in m/s²) of the two blocks.

___ m/s²

(b) What is the tension (in N) in the string connecting the blocks?

____ N

Air has a velocity of 1000 km/h at a pressure of 9.81 kN/m2 in vacuum

and a temperature of 47°C. Compute its stagnation properties and the local Mach number. Take

atmospheric pressure = 98.1 kN/m2, R = 287 J/kg K and γ = 1.4.

What would be the compressibility correction factor for a pitot-static tube to measure the

velocity at a Mach number of 0.8

Air at a pressure of 220 kN/m2 and temperature 27°C is moving at a

velocity of 200 m/s. Calculate the stagnation pressure if

(i) Compressibility is neglected ;

(ii) Compressibility is accounted for.

In aircraft flying at an altitude where the pressure was 35 kPa and

temperature – 38°C, stagnation pressure measured was 65.4 kPa. Calculate the speed of the

aircraft. Take molecular weight of air as 28

A rabbit is moving in the negative x-direction at 1.10 m/s when it spots a predator and accelerates to a velocity of 11.5 m/s along the positive y-axis, all in 1.40 s. Determine the x-component and the y-component of the rabbit's acceleration. (Enter your answers in m/s². Indicate the direction with the signs of your answers.)

(a)

x-component

 m/s²

(b)

y-component

 m/s²

A record of travel along a straight path is as follows:

1. Start from rest with constant acceleration of 2.40 m/s² for 16.0 s.

2. Maintain a constant velocity for the next 1.20 min.

3. Apply a constant negative acceleration of −9.29 m/s² for 4.13 s.

(a) What was the total displacement for the trip?

(b) What were the average speeds for legs 1, 2, and 3 of the trip, as well as for the complete trip?leg 1     

 m/sleg 3     

 m/scomplete trip     

 m/s

Below is a 𝑇𝑉 diagram of a reversible process of a monatomic ideal gas with 𝑛 moles such that 𝑛𝑅 = 2.00 J K −1 . The process traces the curve 𝑇 = (400 K m−3 ) 𝑉 − (100 K m−6 ) 𝑉 2 starting at state 𝑎 with 𝑉𝑎 = 3.00 m3 and ending at state 𝑏 with with 𝑉𝑏 = 1.00 m3.Calculate, for this process (ensure that signed values have the correct sign): (a) Pressures 𝑃𝑎 and 𝑃𝑏 at the endpoints, in Pa (b) Change in internal energy, ∆𝑈, in J (c) Work 𝑊 done by the gas, in J (d) Heat 𝑄 added to the gas, in J (e) Entropy change Δ𝑆 of the gas, in J K.

why entropy is constant in adiabatic process

5. A steady state, steady flow compressor draws in 240 liters per second of air whose density is 1.26

kg m /m 3 and discharges it with a density of 4.9 kg m /m 3 . At suction P 1 = 104 kPaa; at discharge, P 2 = 551

kPaa. The increase of specific internal energy is 78.5 kJ/kg m and the heat from the air by cooling is 30

kJ/kg m . Neglecting the change in potential and kinetic energies, determine the work in kJ/min.

4. A fluid system undergoes a non-flow frictionless process from 4.5 ft 3 to a final volume 1.5 ft 3 in

accordance with the defining relation P= 60/V + 30 psi, where volume in ft 3 . During the process the

system reject 30 BTU of heat. Determine the change in enthalpy and internal energy.