Describe how you would determine the half-life of a substance from an activity/time graph.

If the heat engine is a perfect carnot cycle engine, thenefficiency = (t2-t1)/t2   where t1=temperature of cold reservoir ( ° k) = 135            t2=temperature of hot reservoir ( ° k)   = 325thereforeefficiency = (t2-t1)/t2 = (325-135)/325 = 0.5846 = 58%  note: this is the theoretical maximum efficiency of a perfect heat engine.   real-life engines do not achieve this value.

Ibelieve the answer is d. densityhope my answer has you : )

How are period and frequency related to each other? dperiod is the reciprocal of frequency.

Idon't get it? what do you mean by playing 17 hours on the wii