Question

A bicyclist rides 2.93 km due east, while the resistive force from the air has a magnitude of 8.65 N and points due west. The rider then turns around and rides 2.93 km due west, back to her starting point. The resistive force from the air on the return trip has a magnitude of 8.65 N and points due east. Find the work done by the resistive force during the round trip. Number Type your answer here Units Choose your answer here

Answer 1

Answer:

-50.6 kJ

Explanation:

The work done (W) on an object is given by:

W = (Fcosθ) * S

where F is the force, S is the displacement and θ is the angle between the force and displacement.

i) During the first trip riding east, S₁ = 2.93 km = 2930 m, F₁ = 8.65 N.

The displacement is due east and the force is due west, hence θ₁ = 180°. Therefore:

W₁ = (F₁ * cosθ₁)S₁ = (8,65 * cos(180))2930 = -25.3 kJ

ii) i) During the second trip riding west, S₂ = 2.93 km = 2930 m, F₂ = 8.65 N.

The displacement is due west and the force is due east, hence θ₂ = 180°. Therefore:

W₂ = (F₂ * cosθ₂)S₂ = (8,65 * cos(180))2930 = -25.3 kJ

work done by the resistive force during the round trip is:

W = W₁ + W₂ = -25.3 kJ + (-25.3 kJ) = -50.6 kJ