Physics: Pressure & Thermometry

Units

100

Newton

What is the SI unit of force?

200

kg/m³

What is the SI unit of density?

300

Pa

What is the SI unit of pressure?

400

Volts 

What is the SI unit for voltage /potential difference (p.d) / e.m.f ?

500

Ohms

What is the SI unit of resistance?

Pressure 1

100

Force applied per unit area

What is pressure?

200

Pressure, in Pa, of a 10N force applied over a square area of length 2 cm.

25000 Pa

300

The maximum pressure a layer of ice on a frozen pond can withstand is 20 kPa.  A man of mass 100 kg stands on the ice. The total surface area of the soles of his shoes is 400 cm².  Will he break the ice?

Yes

400

The maximum pressure the ice on a frozen pond can withstand is 4.3 kPa.  I need to transport an elephant, of mass 3 tonnes, across the pond by placing it on a flat board and dragging it across the ice.  What is the minimum area of the board?

6.98 m²

500

In a hydraulic press, a force of 1540 N is applied on one piston of area 25 cm².  What is the maximum mass that can be supported on the other piston given that the area of the second piston is 4.2 cm²?

25.872 kg

Pressure 2

100

The formula used to calculate pressure in a fluid.

P = density of fluid x g x height of fluid column

200

The name of the instrument that measures atmospheric pressure.

Barometer

300

What is the pressure due to the water on a diver who is 12 m under the surface of water which has a density of 1150 g/cm³?

138 Pa

400

The atmospheric pressure read by a barometer is 78.5 cmHg.  Given that the density of mercury is 13.6 g/cm³, what is the atmospheric pressure in Pa?

106760 Pa

500

A fish swims in the ocean at a depth of 480 m.  The total downward pressure on it is 106725 Pa.  Given that atmospheric pressure is 101325 Pa, find the average density of the ocean water.

1.125 kg/m³

Thermometry 1

100

The lower fixed point on the Celsius scale, set at 0^oC

The melting point of pure ice

200

What is a thermometric property?

A physical property that varies continuously with temperature.

300

What assumption do we make about thermometric properties on which temperature scales are based, but that lead to inaccuracies in the thermometer?

That thermometric properties vary uniformly with temperature / 

The the change in the value of the thermometric property is that same over each 1^oC change in temperature.

400

The lengths of the thread in an alcohol-in-glass thermometer in ice point and steam point are 4.2 cm and 18.7 cm respectively.  

The thermometer is then placed in a class of water and the length of the thread becomes 20.0 cm.  What is the temperature of the water?

109^oC

500

The thermocouple shows a reading of 2.5 mV when the hot junction is placed in a beaker of water with a temperature of 30^oC.

What is the reading of the voltmeter reading when the hot junction is placed pure boiling water?

8.33 mV

Thermometery 2

100

The upper fixed point on the Celsium scale, set at 100^oC

Boiling point of pure water 

200

The thermometric property of thermocouple

Potential difference / voltage between the hot and cold junctions.

300

The lengths of the thread in two mercury-in-glass thermometers, A and B, are 2 cm and 5 cm at ice point, and 20 cm and 30 cm at steam point respectively.  Which thermometer is more precise?

Thermometer B

400

The lengths of the thread in an mercury-in-glass thermometer in ice point and steam point are 1.9 cm and 20.5 cm respectively.  

The thermometer is then placed in a class of water of temperature 14.7^oC.  What is the length of the thread?

4.63 cm

500

A resistance thermometer shows a reading of 8.5 ohms and 14.8 ohms respectively when placed in temperatures of 45^oC and steam point respectively.

What is the reading of the resistance thermometer at ice point?

3.35 ohms