Question

a skier is traveling fast down a mountain slope. the table shows data collected on the skier at a particular instant.

mass	64 kg
weight	608 n
velocity	21 m/s, forward
force of skier pushing forward	45 n, forward

which data are needed to determine the reaction force of the snow pushing on the skier?

a. the force of the skier pushing forward
b. the skier’s mass and velocity
c. the pushing force and the skier’s mass
d. the skier’s weight and acceleration

Explanation:

To determine the reaction force of the snow pushing on the skier, we use Newton's Third Law, which states that for every action, there is an equal and opposite reaction. The action force here is the force of the skier pushing forward on the snow. By Newton's Third Law, the reaction force (snow pushing on skier) is equal in magnitude and opposite in direction to the action force (skier pushing on snow). So we only need the force of the skier pushing forward.

• Option B: Mass and velocity are related to momentum or kinetic energy, not reaction forces via Newton's Third Law.
• Option C: Mass is not needed for reaction force (Newton's Third Law depends on action - reaction pair, not mass).
• Option D: Weight and acceleration are related to net force (Newton's Second Law, \(F = ma\)) and not directly to reaction force via Newton's Third Law.

Answer:

A. The force of the skier pushing forward