Exam 11: Energy in Thermal Processes

A solar heated house loses about 5.5 × 10⁷ cal through its outer surfaces on a typical 24-h winter day.What mass of storage rock is needed to provide this amount of heat if it is brought up to initial temperature of 58°C by the solar collectors and the house is maintained at 23°C? (Specific heat of rock is 0.21 cal/g⋅°C. )

If heat is flowing from a table to a block of ice moving across the table,which of the following must be true?

A 38.0-kg cheetah accelerates from rest to 26.0 m/s in 3.00 seconds. Assume the cheetah converts food energy to mechanical energy with an efficiency of 25.0% -What is the maximum rate at which the cheetah is burning Calories?

If cooking is done using an aluminum pan over an electric burner,which of the following will not promote the rate of heat flow from burner to food?

I take 2.0 kg of ice and dump it into 2.3 kg of water and,when equilibrium is reached,I have 4.3 kg of ice at 0°C.The water was originally at 0°C.The specific heat of water = 1.00 kcal/kg⋅°C,the specific heat of ice = 0.500 kcal/kg⋅°C,and the latent heat of fusion of water is 80.0 kcal/kg.The original temperature of the ice was

Calories of the food type are equal to which of the following?

A 0.200-kg aluminum plate,initially at 20°C,slides down a 13.0-m-long surface,inclined at a 25.0° angle to the horizontal.The force of kinetic friction exactly balances the component of gravity down the plane so that the plate,once started,glides down at constant velocity.If 90% of the mechanical energy of the system is absorbed by the aluminum,what is its temperature increase at the bottom of the incline? (Specific heat for aluminum is 900 J/kg⋅°C. )

A metal bar is used to conduct heat.When the temperature at one end is 88.0°C and at the other is 15.0°C,heat is transferred at a rate of 19.0 J/s.The bar is then stretched uniformly to twice its original length.If again it has ends at 88.0°C and 15.0°C,at what rate will heat be transferred between it ends?

A puddle holds 160.0 g of water.If 0.5 g of water evaporates from the surface,what is the approximate temperature change of the remaining water? (L_v = 540 cal/g)

The surface of the Sun has a temperature of about 5 770 K.If the radius of the Sun is 7 × 10⁸ m,determine the power output of the Sun.(Take e = 1,and σ = 5.67 × 10−⁸ W/m²⋅K⁴).

A 5.0-g lead bullet traveling in 19.0°C air at 300 m/s strikes a flat steel plate and stops.What is the final temperature of the lead bullet? (Assume the bullet retains all heat. )The melting point of lead is 327°C.The specific heat of lead is 0.128 J/g⋅°C.The heat of fusion of lead is 24.5 J/g.

In the text there is a table of coefficients of linear (α)and volume (β)expansions due to temperature changes.For the solid materials in this list,there is a relationship between α and β which allows you to find the value of β if you know α.Which of the following best describes that relationship?

Who demonstrated that when heat is gained or lost by a system during some process,the gain or loss can be accounted for by an equivalent quantity of mechanical work done on the system?