physics misconceptual questions test 3
Which of the following possibilities could increase the efficiency of a heat engine or an internal combustion engine?
Increase the temperature of the hot part of the system and reduce the temperature of the exhaust. and Decrease the temperatures of both the hot part and the exhaust part of the system by the same amount.
About what percentage of the heat produced by burning gasoline is turned into useful work by a typical automobile? a) 20% b) 50% c) 80% d) 90% e) Nearly 100% .
a
For objects at thermal equilibrium, which of the following is true? a) Each is at the same temperature. b) Each has the same heat. c) Each has the same internal energy. d) All of the above. E) None of the above.
a
Heat is a) the amount of energy transferred between objects as a result of a difference in temperature. b) invisible, odorless, weightless substance. c) measure of the average kinetic energy of atoms. d) fluid called caloric. e) the total kinetic energy of an ideal gas.
a
In an isobaric compression of an ideal gas, a) work is done on the gas. b)the internal energy of the gas remains constant. c) work is done by the gas. d) no heat flows into the gas. e) no work is done on the gas.
a
One mole of an ideal gas in a sealed rigid container is initially at a temperature of 100 ∘C∘C. The temperature is then increased to 200 ∘C∘C. The pressure in the gas a) increases by about 25 %. b)doubles. c) triples. d) remains constant.
a
Two equal-mass liquids, initially at the same temperature, are heated for the same time over the same stove. You measure the temperatures and find that one liquid has a higher temperature than the other. Which liquid has the higher specific heat? a) The cooler one. b)The hotter one. c) Both are the same.
a
An ideal gas undergoes an isothermal expansion from state A to state B. In this process a) Q=0,ΔU<0,W<0 b) Q>0,ΔU=0,W>0 c) Q=0,ΔU>0,W>0 d) Q>0,ΔU=0,W<0 e)Q=0,ΔU=0,W>0
b
As heat is added to water, is it possible for the temperature measured by a thermometer in the water to remain constant? a)No, adding heat will always change the temperature. b) Yes, the water could be changing phase. c)Maybe; it depends on the initial water temperature. d) Maybe; it depends on the rate at which the heat is added.
b
Ten grams of water is added to ten grams of ice in an insulated container. Will all of the ice melt? a) Yes. b) More information is needed. c) No.
b
When an ideal gas is warmed from 20∘C∘C to 40∘C∘C, the gas's temperature TT that appears in the ideal gas law increases by a factor a) that depends on the temperature scale you use b). of 1.07 c) of 2.
b
Which of the following happens when a material undergoes a phase change? a)The chemical composition changes. b) Heat flows into or out of the material. c) The molecules break apart into atoms. d) The temperature changes.
b
A steel plate has a hole in it with a diameter of exactly 1.0 cm when the plate is at a temperature of 20 ∘C∘C. A steel ring has an inner diameter of exactly 1.0 cm at 20 ∘C∘C. Both the plate and the ring are heated to 100 ∘C∘C. Which statement is true? a)The hole in the plate gets larger, and the opening in the ring gets smaller. b)The opening in the ring gets larger, but we need the relative size of the plate and the hole to know what happens to the hole. c) The hole in the plate and the opening in the ring get larger. d) The hole in the plate gets smaller, and the opening in the ring gets larger. e) The hole in the plate and the opening in the ring get smaller.
c
An ideal gas is in a sealed rigid container. The average kinetic energy of the gas molecules depends most on A) the number of molecules in the container. b)the size of the container. c) the temperature of the gas. d) the mass of the molecules.
c
If bottle BB has twice the volume and contains half the number of moles of gas as bottle AA, how does the pressure in BB compare with the pressure in AA? a) PB=1/2PA b) PB=PA c) PB=1/4PA d)PB=2PA e) PB=4PA
c
If the objects are brought into thermal contact, which one will have the greater temperature change? a)The one with the higher initial temperature. b) The one with the higher specific heat. c) The one with the lesser mass. d)The one with the greater mass. e) The one with the lower initial temperature. f) Not enough information.
c
In a mixture of the gases oxygen and helium, which statement is valid? a) The kinetic energy of helium atoms will exceed that of oxygen molecules. b)The oxygen molecules will, on average, be moving more rapidly than the helium atoms. c) The helium atoms will be moving faster than the oxygen molecules, on average. d) Both will be moving at the same speed. e)None of the above.
c
It has been a hot summer, so when you arrive at a lake, you decide to go for a swim even though it is nighttime. The water is cold! The next day, you go swimming again during the hottest part of the day, and even though the air is warmer the water is still almost as cold. Why? a) Water is fairly dense compared with many other liquids. b) Water has a high bulk modulus. c) Water has a high specific heat. d) Water remains in a liquid state for a wide range of temperatures.
c
Rod AA has twice the diameter of rod BB, but both are made of iron and have the same initial length. Both rods are now subjected to the same change in temperature (but remain solid). How would the change in the rods' lengths compare? a)Rod AA > rod BB. b)Rod BB > rod AA. c)Rod AA = rod BB. d)Need to know whether the rods were cooled or heated.
c
The rms speed of the molecules of an ideal gas a) is the same as the most probable speed of the molecules. b) is always equal to √2 times the maximum molecular speed. c) will increase as the temperature of a gas increases. d) All of the above.
c
A heat engine operates between a high temperature of about 600 and a low temperature of about 300. What is the maximum theoretical efficiency for this engine? a) =100%. b)≈66%. c) ≈50%. d) ≈34%. e) Cannot be determined from the given information.
d
An ideal gas undergoes an isobaric compression and then an isovolumetric process that brings it back to its initial temperature. Had the gas undergone one isothermal process instead, a) Need to know the temperature of the isothermal process. b) the work done on the gas would be the same. c) the work done on the gas would be less. d) the work done on the gas would be greater.
d
An ideal gas undergoes an isothermal process. Which of the following statements are true? (i) No heat is added to or removed from the gas. (ii) The internal energy of the gas does not change. (iii) The average kinetic energy of the molecules does not change. a) (i) only. b) (i) and (ii) only. c) (i) and (iii) only. d) (ii) and (iii) only. e) (i) , (ii), and (iii). f) None of the above.
d
On a very hot day, could you cool your kitchen by leaving the refrigerator door open? a) Yes, but it would be very expensive. b) Yes, but only if the humidity is below 50% . C) No, the refrigerator would exhaust the same amount of heat into the room as it takes out of the room. d) No, the heat exhausted by the refrigerator into the room is more than the heat the refrigerator takes out of the room.
d
Radiation is emitted a) only by objects with more caloric than their -surroundings. b) only by objects whose temperature is greater than the temperature of the surroundings. c) only by objects that have a large specific heat. d) by any object not at 0 K. e) only by glowing objects such as the Sun.
d
The linear expansion of a material depends on which of the following? a)The type of material. b)The length of the material. c) The change in temperature of the material. d)All of the above. e) Both the change in temperature and the type of the material.
d
The temperature of an ideal gas increases. Which of the following is true? a) The pressure must decrease. b) The pressure must increase. c) The pressure must increase while the volume decreases. d) The volume must increase while the pressure decreases. e) The pressure, the volume, or both, may increase.
d
Two ideal gases, AA and BB, are at the same temperature. If the molecular mass of the molecules in gas AA is twice that of the molecules in gas BB, the molecules' root-mean-square speed is a)twice as great in BB. b) twice as great in AA. c) 1.4 times greater in AA. the same in both gases. d) 1.4 times greater in BB.
d
When using the ideal gas law, which of the following rules must be obeyed? a) Always use gauge pressure and temperature in degrees Celsius. b) Always use gauge pressure and temperature in kelvins. c) Always use volume in m3 and temperature in kelvins. d) Always use temperature in kelvins and absolute pressure. e) Always use volume in m3 and gauge pressure
d
When you put an ice cube in a glass of warm tea, which of the following happens? a) Cold flows from the ice cube into the tea and heat flows from the tea into the ice cube. b) Cold flows from the ice cube into the tea. c) Neither heat nor cold flows. Only temperature flows between the ice and the tea. d) Heat flows from the tea into the ice cube.
d
Which of the following is not true about an ideal gas? a) The average kinetic energy of the gas molecules increases as the temperature increases. b) The volume of an ideal gas increases with temperature if the pressure is held constant. c) The pressure of an ideal gas increases with temperature if the volume is held constant. d) All gas molecules have the same speed at a particular temperature. e) The molecules are assumed to be far apart compared to their size.
d
A typical thermos bottle has a thin vacuum space between the shiny inner flask (which holds a liquiand the shiny protective outer flask, often stainless steel. The vacuum space is excellent at preventing a)conduction, convection, and radiation. b) radiation. c)convection. d) conduction. e) conduction and convection
e
An ideal gas undergoes an adiabatic expansion, a process in which no heat flows into or out of the gas. As a result, a) the temperature of the gas remains constant and the pressure decreases. b) both the temperature and volume of the gas increase. c) the temperature of the gas decreases and the pressure increases. d) both the temperature and pressure of the gas increase. e) both the temperature and pressure of the gas decrease.
e
