CLASS NO.2

1.The experiment of heating the bimetallic strip：
   When the bimetallic strip was heated, the brass expanded quicker than the invar.

The experiment of cooling the bimetallic strip：

  When the bimetallic was cooled, the brass shrunk quicker than the invar.

When the brass plate was heated, the hole became bigger. However in fact, the ring  expands in both side, its force push ring to be bigger.

2.Linear Thermal Expansion Demo
An one meter metal rod was clamped on one end, and it was heated by hot water. Measure △L.

4. Water and ice were mixed, using heater to heat them in a cup（Procedure ）.

The power of heater：299.2W

Graph：Temperature(℃) VS Time(s) （The graph is not very good because the initial point is not from origin. when ice and water are mixed, the temperature should be 0℃, but it is not.）

Calculating steps

Percent error

Calculating  uncertainty about the value, 0.5 was the smallest increment.

The uncertainty value cannot cover the our error in the experiment, because of operation and human error. When the ice and water are mixed, its temperature should be 0 ℃, but our initial value is not 0 ℃. And during the ice is transferring into cup, few ice has already became water, and it decreases the mass of ice. The last reason is there is not all energy to be used to heat water, but they are lost by heating air.