Question

hockey is a sport in which players use hockey sticks to push a puck across smooth ice. at practice one day, three different - colored hockey pucks were sliding on the ice. the green hockey puck has less mass than the black and purple hockey pucks, which have the same mass. a player hit each hockey puck with a stick, but not from the same direction. use the information in the diagram to answer. which puck(s) experienced the strongest force when hit? how do you know? a. all three hockey pucks experienced the same force because they changed speed by the same amount. b. the black hockey puck; it is more massive and it has the fastest ending speed. c. the purple hockey puck; it takes a stronger force to slow down a more massive object than to speed it up. d. the black and purple hockey pucks; they have more mass than the green puck, but changed speed by the same amount.

Explanation:

To determine which puck experienced the strongest force, we use the concept of force, mass, and acceleration (change in speed). The formula \( F = ma \) (Force = mass × acceleration) tells us that for the same acceleration (change in speed), a greater mass means a greater force.

• Green puck: Mass = 165 g, speed change: Let's calculate. Initial speed: 0 m/s, final speed: 16 m/s? Wait, no, looking at the diagram: Green before: speed 0, after: 16 m/s? Wait, no, the text: Green Puck: 165 g (Less Mass), Speed: 0 m/s (before), after: 16 m/s? Wait, no, the "change in speed" (acceleration-related) – wait, the black and purple have same mass (370 g), green is 165 g.

Black puck: Before speed 26 m/s, after 26 m/s? Wait, no, the diagram labels:

Green Puck: 165 g, Speed before: 0 m/s, after: 16 m/s (change: 16 - 0 = 16 m/s)

Black Puck: 370 g, Speed before: 26 m/s, after: 26 m/s? Wait, no, the "After" for black: Speed: 26 m/s (same as before? No, maybe typo, but the purple: Before speed 27 m/s, after 7 m/s (change: 27 - 7 = 20 m/s? Wait, no, the problem says "changed speed by the same amount" for black and purple? Wait, the options:

Option d: Black and purple have more mass than green, and changed speed by same amount. So using \( F = ma \), same acceleration (Δv) but more mass (m) means more force (F). So black and purple (same mass, 370 g) vs green (165 g). If their Δv is same, then F is proportional to m. So black and purple, with more mass, same Δv, so more force than green.

Option a: Wrong, because mass differs, so same Δv but different mass means different force.

Option b: Black's ending speed is same as before? No, maybe diagram error, but option d says black and purple have more mass, same Δv.

Option c: Wrong, force to slow down or speed up depends on mass and Δv, not direction.

So correct is d: Black and purple, as they have more mass, same speed change as others (or same Δv), so more force.

Answer:

d. The black and purple hockey pucks; they have more mass than the green puck, but changed speed by the same amount.