Question

The backwards (friction) force on the athlete is 42 N, the forwards force of the wind is 21 N, and the force from her muscles is 84 N. Calculate the resultant force on the runner. Give its direction.

Answer 1

The resultant force on the runner is 63 N in the forward direction, obtained by subtracting the backward friction force from the sum of the forward forces due to the wind and the athlete's muscles.

Step-by-step explanation:

To calculate the resultant force on the runner, we simply need to consider the vector sum of all the forces acting on the runner. We have a backwards force (friction) of 42 N, a forwards wind force of 21 N, and a forwards force from the athlete's muscles of 84 N. Resultant force (Fres) is thus the sum of the forward forces minus the backward force: Fres = (84 N + 21 N) - 42 N = 63 N. The direction of the resultant force is forwards since the sum of the forward forces is greater than the backwards force.