Problem

(II) At the instant a race began, a 65-kg sprinter exerted a force of 720 N on the starting block at a 22° angle with respect to the ground, (a) What was the horizontal acceleration of the sprinter? (h) If the force was exerted for 0.32 s, with what speed did the sprinter leave the starting block?

Solution 30P: If a force is applied at angle to the block, then only the part (component) is responsible for creating an acceleration along horizontal direction. We have to calculate the value of horizontal acceleration and the final speed of the block after the force was removed. Step 1 of 4 Concept:Newton’s second law: The net force F acting on an object of mass m produces an acceleration a in that object. Mathematically, F = ma. Free body diagram of a body gives the diagrammatical representation of all the forces acting on the body in terms of magnitude and diagram, under the given situation. Step 2 of 4 Figure below shows the free body diagram of the block o F = 720 N Force Applied at an angle = 22 F x Fcos Horizontal component of F F y Fsin Vertical component of F m = 65 kg Mass of sprinter Taking positive direction along positive x-axis and vice versa