A study question tests what a difference between two groups lets you conclude. Name each group and its results, then check what the study kept the same. If the passage gives both a total and its parts, track those separately. Ask how the parts add up: with equal totals, a larger amount in one part leaves a smaller amount in the other. Wrong choices often confuse a difference in one part with a difference in the whole.
Hints
- Hint 1
The wheels have the same total mass. Compare their measured forward speeds and ask what speed tells you about energy in forward motion when mass stays the same.
- Hint 2
Look at how the total energy is divided. What do the calculations tell you about the totals, and how can you use that to compare the two parts?
Step-by-step
Compare the parts of the total
Step 1Compare energy in forward motion
The sensors showed that the axle-weighted wheel had a higher forward speed, which gives us a starting point for the blank's conclusion about energy. Why does having the same mass matter here? They have the same total mass, and for equal masses, higher speed means more kinetic energy in forward motion. So the axle-weighted wheel has more energy in forward motion than the rim-weighted wheel, but we still need to account for rotation.
- Step 2
Separate the total from its parts
What do the calculations tell us about total energy? The wheels had nearly the same total kinetic energy, and that total includes both forward motion and rotation. That means we should read the total as two parts added together, not as another name for forward speed. The totals nearly match even though the forward-motion parts differ, so we have to account for the difference in the rotational parts.
- Step 3
Work out which wheel has more rotational energy
Which wheel must then have more energy in rotation? With nearly the same total kinetic energy, the axle-weighted wheel's larger forward-motion part leaves a smaller rotational part. If the wheels had nearly identical rotational energies, that wouldn't balance their different forward-motion energies. The rim-weighted wheel must instead have more energy in rotation and less in forward motion, which is the split this choice describes. Choice C.