In order to fnd the specifc heat c of an unknown substance, you place 75 g of the substance in a 30 g copper calorimeter that contains 65 g of water, all initially at 20 °C. You then add 100 g of water at 80 °C, and measure the fnal temperature of the system to be 49 °C. Assuming no heat is lost to the environment, what is c? [Answer: c = 2200 J/kg. K]

A student evaluates a weight loss program by calculating the number of times he would need to climb a 11.0 m high flight of steps in order to lose one pound (0.45 kg) of fat. Metabolizing 1.00 kg of fat can release 3.77 ✕ 107 J of chemical energy and the body can convert about 19.4% of this into mechanical energy (the rest goes into internal energy.)   (a)How much mechanical energy (in J) can the body produce from 0.450 kg of fat?   (b)How many trips up the flight of steps are required for the 74.0 kg student to lose 0.450 kg of fat? Ignore the relatively small amount of energy required to return down the stairs.

Unit systema) Determine the units of pressure in the equation pv=RT v: specific volume, m3/kg R: constant in kJ/kgK, T: temperature in K

1. Composite Brick Wall A 3.0 in thick brick wall has an outside surface temperature of 15 o F at a certain time in severe winter weather. The inside 0.5 in thick wallboard, which is separated from the brick wall by a 6-in air gap, has an inside surface temperature of 78 o F. Determine (a) the R-value Rv of the wall and (b) the heat rate q'' in [Btu/h·ft 2 ] through this wall. Assume that the air between the brick and wallboard surfaces does not circulate.

Homework

1.3 A mixture of two liquids of equal volume is made, the one has a relative density of 0,8 and the other a density of 980 kg/m³. What will the weight of 2 500 litres be? 1.4 1.5 1.6 15 1.7 [21830 N] A solid block of stone with a relative density 4 is broken down and crushed to an average size of 20 mm. If the stone originally had a volume of 50 m³, how many truck loads with a volume of 2 m³, will it take to transport the crushed stone if 25 of the crushed stone has a mass of 80 kg. Has the relative density changed? How much? Why? [32 truck loads] Use table 1.4.2 to determine the kinematic viscosity of crude oil with a density of 855 kg/ m³ at temperatures of 20°C and 100°C. [9,357 x 10-6 m²/s; 3,275 x 10-6 m²/s] Air is used in a sensitive gyroscope to keep the metal bearing surfaces apart. Will the friction losses in the bearing be higher, lower or the same if the temperature of the bearing increases? A widely used S.I. unit for kinematic viscosity is centi- stoke cSt. One stoke is…

Calculate the make up rate of the water by doing a material balance between the water stream and the air stream. Show your steps of calculation. (Attached are the datasets)

The temperature of a system rises by 120°C during a heating process. Express this rise in temperature in kelvin. The rise in temperature is 393 K. 2 5 8

A 370-g sample of an unknown (nongaseous) material experiences a 24.0°C increase in temperature after absorbing 1.24 x 103) of energy. (a) What is the specific heat of this material? 3400 Your response differs significantly from the correct answer. Rework your solution from the beginning and check each step carefully. J/(kg. °C)

Thermodynamics. Help me to answer this question  By referring to the thermodynamics tables, calculate the missing properties in the following table and determine the phase for each subtance.