Question

FOR BRAINLIEST!!!!!

Heat radiations travel in vacuum with a speed equal to:

3 x 108 m/s

3 x 1010 m/s

330 m/s

3 x 106 m/s


An amount of heat equal to 10.5 x 105 J is supplied to 5 kg of water to raise its temperature from 25°C to 75°C. What is the specific heat capacity of water?

4.2 J/kg.°C

4200 J/kg.°C

1000 J/kg.°C

4200 kcal/kg.°C


540 g of ice at 0°C is mixed with 540 g of water at 80°C. What is the final temperature of the mixture?

0°C

40°C

80°C

less than 0°C


If ∆Q is the heat supplied to a gas so that the internal energy of the system increases by ∆U, then the work done ∆W by the gas is equal to:

∆Q – ∆U

∆Q + ∆U

∆Q x ∆U

∆U/∆Q


The internal energy of the gas in a gasoline engine cylinder decreases by 210 J. If 60 J of work is done by the gas, the energy transferred as heat is:

270 J

150 J

-150 J

-270 J


A gaseous refrigerant undergoes compression over 160 J of work done on it. If the internal energy of the gas increases by 130 J, the amount of heat transfer is:

290 J

-290 J

30 J

-30 J


A steam engine converts 150 kg of water completely to steam. The process involves transfer of 4 x 108 J as heat. If steam escaping through the safety valve does 2 x 108 J of work against outside atmosphere, the net change in the internal energy is:

2 J

2 x 108 J

6 J

6 x 108 J


In a thermodynamic process, the volume of the system remains constant. What is this process called?

isothermal

isobaric

adiabatic

isovolumic


A gas undergoes isothermal change. Which of the following remains constant?

heat content

pressure

temperature

volume


In an adiabatic process, the internal energy of a gas decreases by 350J.The energy transferred as heat is:

0 J

350 J

-350 J

none of the above


The internal energy of the gas in a gasoline engine's cylinder decreases by 200 J. If 50 J of work is done by the gas, how much energy is added or removed as heat?

150 J added as heat.

150 J removed as heat.

250 J added as heat.

250 J removed as heat.


Energy is transferred to a gas as heat and work. What is the process known if there is no change in its internal energy?

isothermal

isobaric

adiabatic

isovolumic

Answer 1

2.1 We calculate the total mass of air M. The mass is equal to the volume multiplied

by the density. It is proper to notice the units used here: 1 g cm−3 and

1 L = 1000 cm3, whose product gives the unit of mass, i.e., 1 kg. We get

M = Vρ = 22 × 1000 cm3 × 10−3 g cm−3 = 22 g = 0.022 kg.

We neglect the fact that air is composed mainly of N2 (78 %) and O2 (21 %). Then

we use the expression for the kinetic energy. Assuming that all molecules have an

average speed of about v = 300 m s−1, which corresponds roughly to the speed of

sound in air, we obtain the kinetic energy:

E = Mv2

2 = 22 g × (300)

2 m2 s

−2/2 = 1980 J/2 ≈ 1 kJ.