Science Assessment ~ Topics ~ Energy: Forms, Transformation, Transfer, and Conservation ~ Item RG176001 ~ Student Performance

A man pushes a shopping cart through the grocery store at a constant speed of 1 m/s as shown in Figure 1. He fills his cart so that the mass of the cart and its contents is twice as much as the mass of the empty cart. He continues to push the cart at 1 m/s as shown in Figure 2.

When the shopping cart doubles in mass, what will happen to the kinetic energy (motion energy) of the cart and its contents?

The kinetic energy will be half of what it was because the amount of kinetic energy an object has is inversely proportional to its mass.
The kinetic energy will be double what it was because the amount of kinetic energy an object has is directly proportional to its mass.
The kinetic energy will be double what it was because the man is now pushing harder and kinetic energy depends on the effort required to move an object.
The kinetic energy of the cart will stay the same because the amount of kinetic energy an object has depends only on its speed and not its mass.

Distribution of responses
Answer Choice	Overall	Grades			Gender		Primary Language
	n = 1635	4–5 n = 0	6–8 n = 845	9–12 n = 790	Male n = 753	Female n = 853	English n = 1435	Other n = 151
A.	25%	N/A	28%	22%	25%	25%	24%	33%
B.	36%	N/A	33%	39%	38%	34%	37%	29%
C.	26%	N/A	26%	26%	25%	27%	26%	23%
D.	13%	N/A	13%	13%	13%	13%	13%	15%

Science Assessment

Item RG176001: Kinetic energy is proportional to mass, so when a moving object has its mass increased by two the kinetic energy of that object increases by two.