Following a collision in outer space, a copper disk at 850°C is rotating about its axis with an angular speed of 25.0 rad/s. As the disk radiates infrared light, its temperature falls to 20.0°C. No external torque acts on the disk. (a) Does the angular speed change as the disk cools off? Explain why. (b) What is its angular speed at the lower temperature?

Following a collision in outer space, a copper disk at 850°C is rotating about its axis with an angular speed of 25.0 rad/s. As the disk radiates infrared light, its temperature falls to 20.0°C. No external torque acts on the disk. (a) Does the angular speed change as the disk cools off? Explain why. (b) What is its angular speed at the lower temperature?

Physics for Scientists and Engineers: Foundations and Connections

1st Edition

ISBN:9781133939146

Author:Katz, Debora M.

Publisher:Katz, Debora M.

Chapter19: Temperature, Thermal Expansion And Gas Laws

Section: Chapter Questions

Problem 61PQ

See similar textbooks

Similar questions

A gas is at 200 K. If we wish to double the rms speed of the molecules of the gas, to what value must we raise its temperature? (a) 283 K (b) 400 K (c) 566 K (d) 800 K (e) 1 130 K
A. 1 kg of ice at 0°C is mixed with 3 kg of steam at 100°C in a thermally isolated container and allowed to reach thermal equilibrium. What is the final temperature of the resulting mixture? The latent heat of fusion is 80 cal/g and the latent heat of vaporization is 540 cal/g. The specific heat of water is 1.00 cal/g · K. The specific heat of both ice and steam is 0.5 cal/g · K° B. A skater spins with constant angular acceleration from rest to a final angular speed of 10.0 rev/s in 6.00 seconds. How many revolutions did she make in the first 6.00 seconds? C. A particle exhibiting simple harmonic motion has a velocity v(t) = 200 sin(50t) where v is in m/s. Its maximum velocity in m/s is _______. D. A container has 0.50 kg of ice at 0.00°C. A tube connected from a boiler et 0.100 kg of steam at 100.0°C inside the container. What is the temperature of the system when it has reached equilibrium? Assume that no heat is absorbed by the container.
You mix mI = 1.2 kg of ice at TI = -21°C with mW = 4.8 kg of water at TW = 72°C in an insulated container. The specific heats of ice and water are cI = 2.10×103 J/(kg⋅°C) and cW = 4.19×103 J/(kg⋅°C), respectively, and the latent heat of fusion for water is Lf = 3.34 × 105 J/kg. Enter an expression for the final equilibrium temperature of the mixture in terms of the defined quantities.
Two identical concrete slabs lie flat and in contact with each other as shown in the figure. If the temperature increases by 100 °F, the lower edges opposite the contact edges remained fixed in position, and the lower edges of the contact side remain in contact, what distance x the slabs rise? The coefficient of thermal expansion of the concrete is 40 × 10-6/K. The initial slab length is 5 m.
A shell-and-tube heat exchanger with 2-shell passes and 12-tube passes is used to heat water (cp = 4180 J/kg·K) with ethylene glycol (cp = 2680 J/kg·K). Water enters the tubes at 22°C at a rate of 0.8 kg/s and leaves at 70°C. Ethylene glycol enters the shell at 110°C and leaves at 60°C. If the overall heat transfer coefficient based on the tube side is 280 W/m2·K, determine the rate of heat transfer and the heat transfer surface area on the tube side.
A certain molecule has f degrees of freedom. Show that an ideal gas consisting of such molecules has the following properties: (a) its total internal energy is fnRT/2, (b) its molar specific heat at constant volume is fR/2, (c) its molar specific heat at constant pressure is (f + 2)R/2, and (d) its specific heat ratio is γ = CP/CV = (f + 2)/f.
Following a collision between a large spacecraft and an asteroid, a copper disk of radius 28.0 m and thickness 1.20 m at a temperature of 850°C is floating in space, rotating about its symmetry axis with an angular speed of25.0 rad/s. As the disk radiates infrared light, its temperature falls to 20.0°C. No external torque acts on the disk. (a) Find the change in kinetic energy of the disk. (b) Find the change in internal energy of the disk. (c) Find theamount of energy it radiates.
Suppose due to a bad break of your femur, you require the insertion of a titanium rod to help the fracture heal. The coefficient of linear expansion for titanium is α = 8.60 × 10−6 K−1, and the length of the rod when it is in equilibrium with the leg bone and muscle at 37.0°C is 6.50 cm. How much shorter was the rod at room temperature (20.0°C)?
In a calorimetry experiment, three samples A, B, and C with TA > TB > TC are placed in thermal contact. When the samples have reached thermal equilibrium at a common temperature T, which one of the following must be true? (a) QA > QB > QC (b) QA < 0, QB < 0, and QC > 0 (c) T > TB (d) T < TB (e) TA > T > TC .
On a multi-layered square wall, the thermal resistance of the first layer is 0.005 ° C / W, the resistance of the second layer is 0.2 ° C / W, and the third layer is 0.1 ° C / W. The overall temperature gradient in the wall is multilayered from one side. to the other side is 60 ° C. a. Determine the heat flux through the walls. = Answer watts / m2. b. If the thermal resistance of the second layer is changed to 0.3 ° C / W, what is the effect in% on heat flux, assuming the temperature gradient remains the same? = Answer Answer %.
If the average kinetic energy of the molecules in a mole of N2O gas (nitrous oxide, aka "laughing gas", which behaves as an ideal gas) is 6.5 × 10−21 J, what is the temperature of the gas? a) 0.0 °C b) 20 °C c) 30 °C d) 40 °C e) 50 °C
Consider a 55-cm-long journal bearing that is lubricated with oil whose viscosity is 0.1 kg/m?s at 20°C at the beginning of operation and 0.008 kg/m?s at the anticipated steady operating temperature of 80°C. The diameter of the shaft is 8 cm, and the average gap between the shaft and the journal is 0.08 cm. Determine the torque needed to overcome the bearing friction initially and during steady operation when the shaft is rotated at 1500 rpm.