Final answer:
The magnitude of the velocity of a hockey puck just before it touches the ground, after sliding off a table with an initial velocity of 20.0 m/s and falling from a height of 2.0 m, is 22 m/s.
Step-by-step explanation:
The problem described is an application of kinematics in two dimensions for a projectile motion scenario. We can find the velocity of the hockey puck just before it touches the ground by splitting the motion into horizontal and vertical components. The horizontal velocity remains constant due to the absence of horizontal forces, while the vertical velocity increases due to gravity. To find the final velocity just before touching the ground, we use the kinematic equation for vertical motion v^2 = u^2 + 2gh, where v is the final vertical velocity, u is the initial vertical velocity (which is zero as it starts horizontal), g is the acceleration due to gravity (9.8 m/s^2), and h is the height of the table (2.0 m).
Solving this equation, we get the final vertical velocity. To find the total velocity of the puck just before it touches the ground, we combine the known horizontal velocity of 20.0 m/s with the final vertical velocity using Pythagoras' theorem:
v_total = √(v_horizontal^2 + v_vertical^2). By computing the combined velocity, we find the correct answer to be 22 m/s, which corresponds to option b.