Molecular Physics | Thermodynamics Answers

1. A scientist very carefully does mechanical work on a container of liquid sodium. The liquid sodium loses 300 J of energy to its surroundings but gains 250 J of energy overall. How much work did the scientist do?

1. A scientist very carefully does mechanical work on a container of liquid sodium. The liquid sodium loses 300 J of energy to its surroundings but gains 250 J of energy overall. How much work did the scientist do?

Heat flows through a wooden board 30 mm thick at 0.0086 W/cm³ ,when one of its sides is 20˚C warmer than the other. Determine the thermal conductivity of the wood.

A small probe is made of stainless steel and has a length of 164.1 mm when being used to monitor the temperature in a furnace.

When the probe is removed for maintenance and allowed to cool to 20.0°C the length of the probe is measured as 162.2 mm.

What is the temperature of the furnace? (to 3 s.f and in °C)

[αsteel = 16.0×10−6 K−1]

A poorly ventilated commercial kitchen contains 120 kg of air at a temperature of 19°C and and with a relative humidity of 30% at the start of the evening shift.


At the end of the shift the temperature in the kitchen is 28°C and water is condensing on the walls and ceilings.


What is the minimum amount of water vapour that has been added to the air in the kitchen over the course of the shift? (to 2 s.f and in kg)

A small probe is made of stainless steel and has a length of 164.1 mm when being used to monitor the temperature in a furnace.

When the probe is removed for maintenance and allowed to cool to 20.0°C the length of the probe is measured as 162.2 mm.

What is the temperature of the furnace? (to 3 s.f and in °C)

[αsteel = 16.0×10−6 K−1]

You are jogging along at a slow speed on a cool day and are losing heat at a rate of 120 W via convection. If your surface area is 0.45 m2, your skin temperature is 26°C. and the air temperature is 17°C then what is the heat transfer coefficient of convection, hconv? (to 2 s.f and in W m−2 K−1)

While helping a friend shift furniture you do 2.2 MJ of mechanical work at and efficiency of 11% (η = 0.11).

How much food energy would you need to ingest in order to prevent weight loss? (to 2 s.f and in MJ)

A student is doing an experiment using a 200 W heat plate. He is heating a 300 g block of ice at -20°C to water at

20°C. How long will it take?

calculate steady state temperature of the black body copper disc of radius 4cm and mass 10g. at surrounding temperature of 50 C . when kept initially at 25 C.Also determine stefan boltzmann constant