Question

What variables show a direct relationship? Check all that apply.

the speed of a car and the distance traveled
the elevation above sea level and the air temperature
the number of students in a cafeteria and the amount of food consumed
the mass of an icicle and the time it takes to melt
the distance a planet is from the Sun and that planet’s temperature
the mass of a space shuttle and its acceleration through space

Answer 1

Direct relationship means as one variable increases, the other also increases. The pairs that show a direct relationship are:

- the speed of a car and the distance traveled (for a given time, higher speed → more distance)
- the number of students in a cafeteria and the amount of food consumed (more students → more total food eaten)
- the mass of an icicle and the time it takes to melt (larger mass → longer melt time, all else equal)

The others are inverse or not directly proportional (higher elevation → lower temperature; greater planet–Sun distance → lower temperature; greater shuttle mass → lower acceleration for a given thrust).