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Thermal Expansion and Specific Heat Problems. Risorsa per il CLIL di Fisica in lingua inglese

red - Di seguito vengono proposti alcuni problemi sulla dilatazione termica e sul calore specifico, utili per le classi in cui sono attivi dei percorsi CLIL di Fisica in lingua inglese.

Thermal Expansion Problems

1.   A building with a steel framework is 50.0 m high.  How much taller is it on a summer day when the temperature is 31.0 °C than on a -5.0 °C winter day?  The coefficient of linear expansion of steel is 12 x 10^-6/°C.

2.   An aluminum wire that is 100.0 cm long at 10.0 °C is observed to be 100.2 cm long at a temperature of 80.0 °C.  What is the coefficient of linear expansion of the aluminum?

3.   A steel bolt that is 2.000 cm wide needs to fit through a hole that is 1.998 cm wide.  If the hole stays at the same temperature, how many degrees cooler must the bolt be to fit?

4.   The Mendota Bridge is approximately one mile (1600 m) long.  How much does its length increase between the coldest (-30 °C) and the warmest (40 °C) days of the year?  Assume the bridge deck is made of concrete, whose coefficient of linear expansion is 10 x 10^-6/°C

5.   There are about 20 expansion gaps on the Mendota Bridge.  How wide should an engineer make each gap, at a minimum, based on the results of the last problem?

Specific heat problems

1.    Suppose that 79.3 J of heat energy are absorbed by a 111 g chunk of aluminum.  How much does the temperature of the aluminum rise?

2.    A copper penny (mass = 3.20 g) is left out in the sun, and its temperature warms from 22.8°C to 31.4°C.  How much energy did the penny absorb?

3.    A 5.00 g lead bullet is fired into a fencepost.  The initial speed of the bullet is 250 m/s, and when it comes to rest, half of its kinetic energy goes into heating the bullet.  How much does the bullet’s temperature increase?

4.    A 368 g iron ball bearing is dropped from a 17th story window, falling 54.4 m onto the sidewalk below.  As the ball lands, 14% of its KE goes into heating up the ball.  How much does the ball’s temperature increase?

5.    An electric heater can deliver 250 J/s of energy to a 355 g sample of water.  How much time will be needed to heat the water from 22.1°C to 98.8°C?

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