Most likely, the answer to the first blank is 'force' and the answer to the second blank is 'acceleration'.
The scenario outright tells us that she thinks something affects the acceleration of the puck, so that's pretty much solved right off the bat.
The scenario says stuff like 'the puck will travel at different speeds depending on how she hits it' and 'thinks the amount she pulls back the hockey stick during the swing'. Essentially, it's telling us that she thinks putting force behind said puck (via her hockey stick), would in turn affect the acceleration of the puck.
Notice that the objective of the paper is determining the effects of MASS and FORCES on the ACCELERATION of an object. By this usage of context clues and process of elimination, we can reinforce that forces (1) and acceleration (2) is the answer out of those 3 most likely/relevant terms.
