Science Assessment ~ Topics ~ Energy: Forms, Transformation, Transfer, and Conservation ~ Item EG052005 ~ Student Performance

A student has two identical balloons filled with helium gas. Balloon 1 and Balloon 2 have the same number of helium atoms in them.

If the thermal energy of the helium in Balloon 1 is increased so that the helium in Balloon 1 has more thermal energy than the helium in Balloon 2, which helium atoms would be moving faster on average?

The helium atoms in Balloon 1 would be moving faster on average.
The helium atoms in Balloon 2 would be moving faster on average.
The helium atoms in Balloon 1 would be moving at the same average speed as the helium atoms in Balloon 2.
The only way to tell which helium atoms would be moving faster on average is to also know the temperature of the helium in each balloon.

Distribution of responses
Answer Choice		Overall	Grades			Gender		Primary Language
		n = 1113	4–5 n = 0	6–8 n = 568	9–12 n = 545	Male n = 522	Female n = 565	English n = 953	Other n = 127
A.	The helium atoms in Balloon 1 would be moving faster on average.	51%	N/A	42%	60%	51%	50%	52%	43%
B.	The helium atoms in Balloon 2 would be moving faster on average.	16%	N/A	19%	12%	14%	17%	15%	18%
C.	The helium atoms in Balloon 1 would be moving at the same average speed as the helium atoms in Balloon 2.	18%	N/A	19%	16%	21%	15%	17%	22%
D.	The only way to tell which helium atoms would be moving faster on average is to also know the temperature of the helium in each balloon.	16%	N/A	20%	12%	15%	18%	16%	17%

Science Assessment

Item EG052005: For two balloons that contain the same number of helium atoms, the helium atoms in the balloon with the greater thermal energy are moving at the greater average speed.