What is the advantage of designing a thermos so that it has a vacuum layer surrounding the area where hot liquids are stored?

Which of the following energy forms are invovled in a nuclear power plant ? heat ,sound , electrical , nuclear ,mechanical

State one advantage and one disadvantage of using a plane mirrior as a driving mirrior

The force acting on a beam was measured under the same operating conditions and a sample of 5 data points was collected. this process was repeated by 3 observers. the pooled standard deviations of these 3 data sets was 1.21. determine the true mean force using all pooled data (with a 95% probability). the result should look like this: true mean = mean +/- margin of error