Molecular Physics | Thermodynamics Answers

A 700 lbm rocket is accelerated at a rate of 20 ft/s2. What total force is required in lbf

if: a) the rocket is moving horizontally and without friction, b) the rocket is moving

vertically upward in a location where g = 31 ft/s2.

Four bodies are located in a region where g = 9.67 m/s2

.Body1 = 750 gm; Body2 = 4 poundals; body3 = 4.5 N and body4 = 32.2 lbf.

a) What is the total mass expressed in lbm?

b) What will be the total weight (lbf) if the bodies are located 15,000 ft above

the earth’s surface? (gravitational acceleration decreases by 0.003 ft/s2

for every 1000 ft ascent above sea level)

c) At what distance (miles) from the earth’s surface will these objects weigh

zero.

The block in figure reaches a velocity of 12m/s in 30m, starting from rest

Compute the coefficient kinetic friction between the block and the ground.

• 718 N
• P = 268 N

A heat engine is supplied with 278 k3/s of heat at a constant fixed temperature of 283°C and the best rejection takes place at 5°C The following results were reported (i) 208 klis are rejected, (ii) 139 klis are rejected, and (ii) 70 kJ/s are rejected Classify which of the results report a reversible cycle or irreversible cycle or impossible results

Water flows through a garden house with inner diameter 1.5 cm at a speed of 2.9 m/s. Calculate the speed of water escape from the nozzle if the opening is reduce to a diameter of 0.50 cm

A heater marked 60°c evaporates 6x10¯³ kg of boiling water in 60 seconds and what is the specific latent heat of vaporization of water in Jkg¯¹

Calculate the one temperature at which Fahrenheit and Celsius thermometers agree with each other

A thermometer which was not accurately calibrated indicates -0.5°c at the lower fixed point, and the 106°c at the upper fixed point. What temperature does the thermometer register when the temperature is 60°c.

The electrical resistance of a platinum wire of zero degree celsius is 9.8 ohmes and 11.0 ohmes at 100 degree celsius. calculate the temperature when the resistance is 10.4 ohms assuming that the change in electrical resistance of the conductor is proportional to the change in temperature

A woman weighing 75 kg stands on a spring scale in elevator. During the first 3 seconds of motion from rest, the tension T in the hoisting cable is 8300 N. The total mass of the elevator , woman scale is 750 kg.

1.Find the vertical acceleration of the elevator.

2.Find the reading R of the scale in Newtons during this interval.

3.Find the upward velocity of the elevator at the end of a 3 seconds.