Question 1

On a sunny day at the beach,the reason the sand gets so hot and the water stays relatively cool is attributed to the difference in which property between water and sand?
A)mass density
B)specific heat
C)temperature
D)thermal conductivity

Accepted Answer

The property that is responsible for the difference in temperature between the water and sand is called specific heat. Water has a higher specific heat than sand, meaning it can absorb more heat energy before its temperature rises. Therefore, the sand becomes much hotter in the sun than the water.

Question 2

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%
-At what average rate is the cheetah burning Calories?
A)4.09 Cal/s
B)12 840 Cal/s
C)4 280 Cal/s
D)1.023 Cal/s

Accepted Answer

The work done by the cheetah can be calculated using the kinetic energy formula: $ \text{KE} = \frac{1}{2}mv^2 $, where $ m = 38.0 \, \text{kg} $ and $ v = 26.0 \, \text{m/s} $. Plugging in the values, we get $ \text{KE} = \frac{1}{2} \times 38.0 \times (26.0)^2 = 12,844 \, \text{J} $. Since the efficiency is 25%, the energy from food converted to mechanical energy is $ 12,844 \, \text{J} $, and the total energy from food is $ 12,844 \, \text{J} / 0.25 = 51,376 \, \text{J} $. To find the rate, divide by the time (3.00 s), which gives $ 17,125.33 \, \text{J/s} $. Converting Joules to Calories (1 Cal = 4.184 kJ), we get $ 17,125.33 \, \text{J/s} / 4184 = 4.09 \, \text{Cal/s} $.

Question 3

A 10.0-kg piece of aluminum (which has a specific heat of 900 J/kg⋅°C)is warmed so that its temperature increases by 6.0 C°.How much heat was transferred into it?
A)5.4E+4 J
B)9.0E-2 J
C)1.1E+4 J
D)3.7E-4 J

Accepted Answer

The heat transferred can be calculated using the formula Q = mcΔT, where m is the mass, c is the specific heat, and ΔT is the temperature change. Substituting the given values: Q = 10.0 kg * 900 J/kg°C * 6.0°C = 54,000 J, which is 5.4E+4 J.

Question 4

Heat flow occurs between two bodies in thermal contact when they differ in what property?
A)mass
B)specific heat
C)density
D)temperature

Accepted Answer

Heat flow occurs between two bodies in thermal contact when they differ in temperature. Temperature is the measure of the average kinetic energy of the particles in a substance, and heat flows from a hotter object to a cooler object until both reach thermal equilibrium. The other properties listed, such as mass, specific heat, and density, can affect the amount of heat transferred, but they do not initiate the heat flow.

Question 5

Calories of the food type are equal to which of the following?
A)4.186 J
B)4 186 J
C)1 BTU
D)1054 J

Accepted Answer

Calories of food are equal to 4 186 J (joules), which is the amount of energy required to raise the temperature of 1 gram of water by 1 degree Celsius. Choice A is the conversion factor between joules and calories, choice C is the amount of energy required to raise the temperature of 1 pound of water by 1 degree Fahrenheit, and choice D is the conversion factor between calories and joules.

Question 6

How many calories are equal to four BTU? (One calorie = 4.186 J,one BTU = 1 054 J. )
A)1.007
B)15.89
C)1007
D)1589

Accepted Answer

We need to convert four BTU to calories, which can be done by multiplying four by 1,054 (1 BTU = 1,054 J). 
So, four BTU = 4 X 1,054 J = 4,216 J 
Now, we can convert the joules to calories by dividing 4,216 by 4.186 (1 calorie = 4.186 J). 
So, 4,216 J = 1,007 calories. 
Therefore, the answer is C) 1007.

Question 7

The first experiment,which systematically demonstrated the equivalence of mechanical energy and heat,was performed by
A)Joule.
B)Boltzmann.
C)Thompson,Count Rumford.
D)Kelvin.

Accepted Answer

The first experiment that demonstrated the equivalence of mechanical energy and heat was performed by James Prescott Joule in the 1840s. The experiment involved measuring the amount of work it took to stir water in a container and then measuring the resulting increase in temperature of the water, thus showing that mechanical work and heat are interchangeable forms of energy.

Question 8

Sea breezes that occur near the shore are attributed to a difference between land and water with respect to what property?
A)mass density
B)coefficient of volume expansion
C)specific heat
D)emissivity

Accepted Answer

Sea breezes occur due to the difference in specific heat between land and water. Land has a lower specific heat, so it heats up more quickly during the day and cools down more quickly at night, while water has a higher specific heat and changes temperature more slowly. This temperature difference creates a pressure gradient, resulting in the flow of air towards the land during the day (sea breeze) and towards the water at night (land breeze).

Question 9

If a 1 050-kg car was moving at 25 m/s,what would be its kinetic energy expressed in the unusual (for kinetic energy)units of calories? (1 cal = 4.186 J)
A)3.1E+5
B)3.3E+5
C)6.6E+5
D)7.8E+4
E)6.3E+3

Accepted Answer

The answer of If a 1 050-kg car was moving...

Question 10

An inventor develops a stationary cycling device by which an individual,while pedaling,can convert all of the energy expended into heat for warming water.How much mechanical energy is required to increase the temperature of 200 g of water (enough for 1 cup of coffee)from 18°C to 94°C? (1 cal = 4.186 J,the specific heat of water is 4 186 J/kg⋅°C)​
A)6.4E+4 J
B)3.2E+4 J
C)1.6E+4 J
D)1.0E+3 J
E)​1.5E+1 J

Accepted Answer

The energy required is calculated using the formula: Q = mcΔT. Here, m = 0.2 kg, c = 4186 J/kg°C, and ΔT = 94°C - 18°C = 76°C. So, Q = 0.2 * 4186 * 76 = 63665.6 J, which is approximately 6.4E+4 J.

Question 11

Arrange from smallest to largest: the BTU,the joule,and the calorie.
A)BTU,J,cal
B)J,cal,BTU
C)cal,BTU,J
D)J,BTU,cal

Accepted Answer

The joule is the smallest unit among the three, followed by the calorie, and then the BTU (British Thermal Unit) is the largest.

Question 12

As I use sandpaper on some rusty metal,the sandpaper gets hot because:
A)heat is flowing from the sandpaper into the metal.
B)heat is flowing from the metal into the sandpaper.
C)frictional processes increase the internal energy of the sandpaper.
D)heat is flowing from my hand into the sandpaper.

Accepted Answer

When the sandpaper rubs against the rusty metal, friction occurs which increases the internal energy of the sandpaper. This increase in internal energy causes the sandpaper to become hot. Therefore, option C is the correct choice. Heat is not flowing from the sandpaper into the metal or vice versa, and there is no mention of the involvement of hands in the given scenario.

Question 13

Which of the following statements is true?
A)A hot object contains a lot of heat.
B)A cold object contains only a little heat.
C)Objects do not contain heat.
D)Statements a and b are true.

Accepted Answer

Objects do not contain heat; instead, heat is energy in transit between objects of different temperatures. The concept of an object "containing" heat is a common misconception. Heat is the transfer of thermal energy, not a substance contained within an object.

Question 14

If heat is flowing from a table to a block of ice moving across the table,which of the following must be true?
A)The table is rough and there is friction between the table and ice.
B)The ice is cooler than the table.
C)The ice is changing phase.
D)All three are possible,but none is absolutely necessary.

Accepted Answer

Heat always flows from hotter objects to cooler objects. Therefore, if heat is flowing from the table to the block of ice, it means that the ice is cooler than the table. The other options (A and C) are not necessarily true in this situation. There could be friction between the table and ice, but it is not a necessary condition for heat transfer. Similarly, the ice could be changing phase, but there is no information given in the question that suggests this. Therefore, the best choice is B.

Question 15

Marc attaches a falling 328-kg object with a rope through a pulley to a paddle wheel shaft.He places the system in a well-insulated tank holding 23.2 kg of water.When the object falls,it causes the paddle wheel to rotate and churn the water.If the object falls a vertical distance of 88.6 m at constant speed,what is the temperature change of the water? (1 kcal = 4 186 J,the specific heat of water is 4 186 J/kg⋅°C,and g = 9.80 m/s²) A)17 000 C° B)2 930 C° C)2.93 C° D)0.587 C° E)5.87 C°

Accepted Answer

First, we need to find the gravitational potential energy that is converted into thermal energy in the water:
ΔE = mgh = (328 kg) x (9.80 m/s^2) x (88.6 m) = 286078.4 J

Next, we need to find the mass of the water that is heated:
m_water = 23.2 kg

Then, we use the specific heat of water to find the change in temperature:
ΔT = ΔE / (m_water x c_water) = 286078.4 J / (23.2 kg x 4,186 J/kg⋅°C) ≈ 2.93°C

Therefore, the answer is C) 2.93°C.

Question 16

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?
A)2.05 Cal/s
B)8 560 Cal/s
C)8.18 Cal/s
D)6 420 Cal/s

Accepted Answer

First, we need to find the total mechanical energy (TME) that the cheetah gains during the acceleration:

TME = (1/2)mv^2 = (1/2)(38.0 kg)(26.0 m/s)^2 = 12,404 J

Since the cheetah's efficiency is 25%, then only 25% of the chemical energy from food is converted to mechanical energy. Therefore, we can calculate the amount of chemical energy (CE) that the cheetah is using per second:

CE = (TME/efficiency) / time = (12,404 J / 0.25) / 3.00 s = 49,616 J/s = 49,616 W

Finally, we can convert this to Calories per second:

Cal/s = W / 4.18 J/cal = 11,861 cal/s

Rounding to two significant figures and accounting for significant digits in the question, we get:

Cal/s = 8.18 Cal/s

Therefore, the best choice is C.

Question 17

An inventor develops a stationary cycling device by which an individual,while pedaling,can convert all of the energy expended into heat for warming water.What minimum power must be generated if 210 g water (enough for 1 cup of coffee)is to be heated in 14.0 min from 26.0°C to 84.0°C? (1 cal = 4.186 J,the specific heat of water is 4 186 J/kg⋅°C)
A)3 640 W
B)289 W
C)60.7 W
D)850 W
E)42.5 W

Accepted Answer

To find the minimum power, first calculate the energy required to heat the water using the formula: Q = mcΔT. Here, m = 0.210 kg, c = 4186 J/kg°C, and ΔT = 84.0°C - 26.0°C = 58.0°C. So, Q = 0.210 kg * 4186 J/kg°C * 58.0°C = 50,946.12 J. The time is 14.0 min = 840 s. Power is energy divided by time: P = Q/t = 50,946.12 J / 840 s ≈ 60.7 W.

Question 18

A typical avocado has 180 Calories.If all this energy could be used to lift a bucket of water weighing 40 N,through what vertical distance could the bucket be lifted? (1 calorie = 4.184 J and 1 Calorie = 10³ calories) A)1.72E+6 m B)3.01E+7 m C)7.53E+5 m D)1.88E+4 m

Accepted Answer

The energy in the avocado is 180 Calories, which is 180,000 calories or 753,120 Joules (since 1 Calorie = 1000 calories and 1 calorie = 4.184 J). The work done to lift the bucket is equal to the energy, so using the formula Work = Force x Distance, we have 753,120 J = 40 N x Distance. Solving for Distance gives 18,828 m, which is approximately 1.88E+4 m.

Question 19

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?
A)Joule
B)Boltzmann
C)Thompson,Count Rumford
D)Kelvin

Accepted Answer

This is known as the first law of thermodynamics, which was demonstrated by James Prescott Joule.

Question 20

Of the following systems,which contains the most heat?
A)100 kg of water at 80°C
B)250 kg of water at 40°C
C)600 kg of ice at 0°C
D)Systems do not contain heat.

Accepted Answer

Heat is energy in transit due to temperature difference, not a property contained within a system.

Quiz 11: Energy in Thermal Processes

On a sunny day at the beach,the reason the sand gets so hot and the water stays relatively cool is attributed to the difference in which property between water and sand?

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% -At what average rate is the cheetah burning Calories?

A 10.0-kg piece of aluminum (which has a specific heat of 900 J/kg⋅°C) is warmed so that its temperature increases by 6.0 C°.How much heat was transferred into it?

Heat flow occurs between two bodies in thermal contact when they differ in what property?

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

How many calories are equal to four BTU? (One calorie = 4.186 J,one BTU = 1 054 J. )

The first experiment,which systematically demonstrated the equivalence of mechanical energy and heat,was performed by

Sea breezes that occur near the shore are attributed to a difference between land and water with respect to what property?

If a 1 050-kg car was moving at 25 m/s,what would be its kinetic energy expressed in the unusual (for kinetic energy) units of calories? (1 cal = 4.186 J)

Arrange from smallest to largest: the BTU,the joule,and the calorie.

As I use sandpaper on some rusty metal,the sandpaper gets hot because:

Which of the following statements is true?

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?

A typical avocado has 180 Calories.If all this energy could be used to lift a bucket of water weighing 40 N,through what vertical distance could the bucket be lifted? (1 calorie = 4.184 J and 1 Calorie = 10³ calories)

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?

Of the following systems,which contains the most heat?