Q1. The coefficient of kinetic friction between a 78kg box and a warehouse floor is 0.21. How much force is necessary to keep the box, moving at constant velocity across the floor?
Q2. A particle undergoes a displacement Δr of magnitude 57 m in a direction 25° below the x axis. Express Δr in terms of the unit vectors x and y.
Q3. Consider the vectors in the figure below, in which the magnitudes of A, B, C, and D are respectively given by 57 m, 76 m, 38 m, and 57 m. state the sum, A+ B+ D, in unit vector notation.