Question

hockey is a sport in which athletes use hockey sticks to hit a puck across smooth ice. at practice one day three hockey pucks (all with the same mass) were sliding across the ice. a player hit each puck with a hockey stick, but in the same direction. each puck changed speed as a result of being hit. use the information in the diagram to answer. which hockey puck(s) experienced the strongest force when hit? how do you know?
the black puck because it takes a stronger force to slow something down than to speed it up.
all three hockey pucks experienced the same strength force because they changed speed by the same amount.
the green puck experienced the strongest force because it has the fastest ending speed.
the green and red pucks: they both gained the same force as they sped up, but the black puck lost speed slowed down.
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Explanation:

According to Newton's second law \(F = ma\) (where \(F\) is force, \(m\) is mass, and \(a\) is acceleration). Acceleration \(a=\frac{\Delta v}{\Delta t}\). If the time of impact \(\Delta t\) is the same for all pucks (implied in a practice - like scenario where the action of hitting is similar in duration), and the masses \(m\) of the pucks are the same (given in the problem). The change in velocity \(\Delta v\) determines the acceleration. The green and red pucks have positive changes in velocity (speeding up) and the black puck has a negative change in velocity (slowing down). The magnitude of the change in velocity for the green and red pucks (assuming from the context of the problem's options, since they "gained" speed and the black "lost" speed, and if the magnitude of \(\Delta v\) for green and red is the same as the magnitude of \(\Delta v\) for black in terms of force - mass - acceleration relationship) means they experience forces of the same magnitude. Slowing down (negative acceleration) and speeding up (positive acceleration) with the same magnitude of \(\Delta v\) (when \(m\) and \(\Delta t\) are constant) implies the same force magnitude.

Answer:

D. The green and red pucks: they both gained the same force as they sped up, but the black puck lost speed (slowed down).