Which object is most efficient? a. A heat engine that produces 30 J of work for 60 J of input energy.
b. A heat engine that produces 15 J of work for 30 J of input energy.
c. A heat engine that produces 20 J of work for 60 J of input energy.
d. A heat engine that produces 40 J of work for 50 J of input energy.

Zirconium has an hcp crystal structure and a density of 6.51 g/cm3. (a) what is the volume of its unit cell in m3? (b) if the c/a ratio is 1.593, compute the values of c and a.

In the circuit shown below, with each bulb holding a resistance of 60 ohms, how many amps of current are flowing? express your number as a decimal.

While studying chemical reactions and conservation of matter, sarah's class conducted a variety of experiments. sarah and her lab partner found the mass of a wax candle and placed the candle in a flask. the students lit the candle and let it burn to completion. all that was left was wax and charred candle wick. per their teacher's instructions, the students found the mass of the products. their data can be seen in the data table. formulate a hypothesis the students could test to explain why the experiment did not support the law of conservation of matter. a) the students could repeat the experiment using different candles; there might have been a flaw in the candle. b) the experiment should be repeatable. the students should run several trials and then take an average of the after mass in each trial. c) the students should have someone in the class check their measurement skills as they repeat the experiment. they may have made an error using the balance. d) the students should burn the candle in a container that has some type of lid so that any gas that is a product of the reaction can be contained and massed. submit