Question

analyzing the relationship between mass and inertia
li and raj are playing football. they take turns trying to run past each other with the football. li weighs 125 pound and raj weighs 175 pounds. li discovers that if he changes direction quickly when running, he can always dodge out of the way before raj can tackle him.
why is li able to avoid rajs tackle? choose the best description.
○ raj has more mass and therefore more inertia, so he can change his motion more easily than li.
○ raj has more mass and therefore less inertia, so he can change his motion more easily than li.
○ li has less mass and therefore more inertia, so he can change his motion more easily than raj.
○ li has less mass and therefore less inertia, so he can change his motion more easily than raj.

Explanation:

To solve this, we use the concept of inertia: inertia is directly proportional to mass (more mass means more inertia, and more inertia means it's harder to change motion).

• Raj weighs 175 pounds (more mass) → more inertia → harder to change motion.
• Li weighs 125 pounds (less mass) → less inertia → easier to change motion (so he can dodge).

Now analyze each option:

• First option: Says Raj (more mass) can change motion easier, but more inertia means harder to change motion. Wrong.
• Second option: Says more mass means less inertia. Inertia is proportional to mass, so this is wrong.
• Third option: Says less mass means more inertia. Inertia is proportional to mass, so this is wrong.
• Fourth option: Says Li (less mass) has less inertia, so he can change motion easier. This matches the inertia - mass relationship.

Answer:

D. Li has less mass and therefore less inertia, so he can change his motion more easily than Raj.
(Note: In the original options, the fourth option is the correct one. If the options were labeled as A, B, C, D with the fourth being D, then the answer is D. Li has less mass and therefore less inertia, so he can change his motion more easily than Raj.)