Science Assessment ~ Ideas ~ Motion energy (kinetic energy) is associated with the speed and the mass of an object.

Key Idea: When objects collide, contact forces can transfer energy from one object to another resulting in a change in the objects’ motion.

Sub-Ideas
Items & Student Performance
Misconceptions
NGSS

Students should know that:

When two objects collide, their speeds change compared to their speeds before the collision and energy is transferred from the object that slows down to the object that speeds up. [Note: An exception to this is when two identical objects collide at a 45-degree angle. Assessment items will not assess students’ understanding of the exceptions.]
Energy is transferred by forces as long as one object exerts a force on another object. The transfer of energy stops when one object no longer exerts a force on the other object.
When two forces act over the same distance and in the same direction, the stronger force transfers more energy than the weaker force.

Boundaries:

This idea is limited to transfers of energy as a result of direct contact forces and elastic collisions and is limited to systems containing two objects that are moving or that can be moved. Examples of direct contact include when billiard balls hit each other, when a ball is thrown or kicked, when a baseball or golf ball is hit with a bat or club, when an object is set in motion by a rubber band or spring, or when a bobsled or swing is pushed.
Assessment items include contexts where there is a clear transfer of energy (one object will slow down and the other will speed up). Items do not include collisions between objects that are significantly different in mass where the change in speed of the more massive object is negligible.
For direct contact interactions, assessment items may include situations where both objects are moving or one object is moving and the other object is at rest.

Percent of students answering correctly (click on the item ID number to view the item and additional data)
Item ID Number	Knowledge Being Assessed	Grades 4–5	Grades 6–8	Grades 9–12
RG159002	When one car hits another car and the speed of the cars changes, the change in speed is a sign that energy was transferred.	62%	68%	73%
RG099002	After one car bumps into another car, the first car moves slower and second car moves faster because energy was transferred from the first car to the second..	61%	63%	66%
RG095002	Energy is transferred between two balls as the balls hit each other.	61%	59%	70%
RG097002	After one ball collides with another, the first ball moves slower because it transferred energy to the second ball when the balls hit each other.	47%	60%	68%
NG051002	When a rubber band is used to shoot a toy car across the floor, the rubber band has less energy because energy was transferred to the car.	55%	50%	59%
RG096002	After one ball collides with another, the first ball moves slower.	46%	50%	60%
RG098002	After Cart A hits Cart B, Cart A is going slower and Cart B is going faster.	56%	48%	51%
NG050004	Motion energy, not a force, is transferred when one marble hits another one.	25%	24%	23%

Frequency of selecting a misconception
Misconception ID Number	Student Misconception	Grades 4–5	Grades 6–8	Grades 9–12
NGM034	When one object pushes or pulls on another object, a force, not energy, is transferred (AAAS Project 2061, n.d.).	44%	34%	35%
NGM060	Energy can be destroyed (Kruger, 1990; Trumper, 1998).	20%	19%	17%
RGM084	A change in speed is not related to energy transfer (AAAS Project 2061, n.d.). For example, students say "...speed is not related to the transfer of energy."(zzzzen/12).	19%	16%	12%
NGM010	Energy can be created (Kruger, 1990; Lovrude, 2004; Papadouris et al., 2008).	12%	10%	9%
NGM009	An object has energy within it that is used up as the object moves (Brook & Driver, 1984; Kesidou & Duit, 1993; Loverude, 2004; Stead, 1980).	12%	21%	15%
NGM059	Energy cannot be transferred from one object to another (AAAS Project 2061, n.d.).	8%	8%	7%
EGM001	Energy is associated mainly with human beings, not inanimate objects (Finegold & Trumper, 1989; Kruger, 1990; Kruger, Palacino, & Summers, 1992; Leggett, 2003; Liu & Tang, 2004; Solomon, 1983; Stead, 1980; Trumper, 1990, 1993, 1997a, 1997b; Trumper & Gorsky, 1993; Watts, 1983).	9%	7%	7%
EGM035	Springs or other elastic objects have the same amount of elastic energy regardless of how much they are stretched or compressed (AAAS Project 2061, n.d.).	17%	14%	13%

Frequency of selecting a misconception was calculated by dividing the total number of times a misconception was chosen by the number of times it could have been chosen, averaged over the number of students answering the questions within this particular idea.

NGSS Statements
Code	Statement
PS3.C MS	When two objects interact, each one exerts a force on the other that can cause energy to be transferred to or from the object.
PS3.B Grade 4	Energy is present whenever there are moving objects, sound, light, or heat. When objects collide, energy can be transferred from one object to another, thereby changing their motion. In such collisions, some energy is typically also transferred to the surrounding air; as a result, the air gets heated and sound is produced.
PS3.C Grade 4	When objects collide, the contact forces transfer energy so as to change the objects' motions.