CALC? A force in the + x-direction with magnitude F(x) = 18.0 N – (0.530 N/m)x is applied to a 6.00-kg box that is sitting on the horizontal, frictionless surface of a frozen lake. F(x) is the only horizontal force on the box. If the box is initially at rest at x = 0, what is its speed after it has traveled 14.0 m?

Solution 47E Step 1: Work done on the body, W = FS cos Where, F - Force applied and S - Displacement for the body - Angle between force and displacement If both are in same direction, then = 0 Therefore, W = FS Step 2: In this question, they have provided, F(x) = 18.0 N - (0.530 N/m)x We have to find out the magnitude of force after 14 m. Put x = 14 m in the equation. F (14 m) = 18.0 N - (0.530 N/m) 14 m F = 18.0 N - 7.42 N = 10.58 N