Meriam, Kraige & Bolton — Kinetics of Particles: Problem 3_258

3/258 A boy of mass \( m \) is standing initially at rest relative to the moving walkway inclined at the angle \( \theta \) and moving with a constant speed \( u \). He decides to accelerate his progress and starts to walk from point \( A \) with a steadily increasing speed and reaches point \( B \) with a speed \( v_r \) relative to the walkway. During his acceleration he generates a constant average force \( F \) tangent to the walkway between his shoes and the walkway surface. Write the work-energy equations for the motion between \( A \) and \( B \) for his absolute motion and his relative motion and explain the meaning of the term \( m u v_r \). If the boy weighs 150 lb and if \( u = 2 \text{ ft/sec} \), \( s = 30 \text{ ft} \), and \( \theta = 10^\circ \), calculate the power \( P_{\text{rel}} \) developed by the boy as he reaches the speed of 2.5 ft/sec relative to the walkway.