Science Assessment ~ Topics ~ Force and Motion ~ Item FM103001 ~ Student Performance

An object is moving. Every second, the object’s speed is measured. When the clock reads 0 seconds, the object’s speed is 20 miles per hour (mi/hr). When the clock reads 2 seconds, a single constant force begins to act that slows the object down. This force continues to act during the time shown in the table.

Clock →	0 seconds	1 second	2 seconds	3 seconds	4 seconds	5 seconds	6 seconds
Row A	20 mi/hr	20 mi/hr	20 mi/hr	20 mi/hr	20 mi/hr	18 mi/hr	16 mi/hr
Row B	20 mi/hr	20 mi/hr	20 mi/hr	18 mi/hr	16 mi/hr	16 mi/hr	16 mi/hr
Row C	20 mi/hr	20 mi/hr	20 mi/hr	18 mi/hr	16 mi/hr	14 mi/hr	12 mi/hr
Row D	20 mi/hr	20 mi/hr	20 mi/hr	20 mi/hr	14 mi/hr	14 mi/hr	14 mi/hr

Which row of the table could be a correct representation of the object’s speed between 0 seconds and 6 seconds? Assume that if a change in speed has occurred, the change is shown in the table.

Row A
Row B
Row C
Row D

Distribution of responses
Answer Choice		Overall	Grades		Gender		Primary Language
		n = 1796	6–8 n = 1127	9–12 n = 661	Male n = 833	Female n = 917	English n = 1583	Other n = 178
A.	Row A	12%	15%	8%	12%	13%	12%	13%
B.	Row B	19%	20%	19%	19%	20%	19%	25%
C.	Row C	60%	56%	65%	62%	58%	61%	53%
D.	Row D	8%	9%	7%	8%	9%	8%	8%

Science Assessment

Item FM103001: Use of tables of speed versus time, and information about forces acting on an object, to determine the object's speed at various times.