Question

A push broom is being pushed down across a rough floor. The broom moves to the right. A picture of a person standing pushing a broom downward at an angle to the right. There is a velocity vector below the head of the broom pointing right, labeled v. What is the correct free body diagram of the broom? A free body diagram with 4 force vectors. The first vector is pointing downward, labeled F Subscript g Baseline. The second is pointing right, labeled F Subscript p Baseline. The third vector is pointing upward, labeled F Subscript N Baseline. The fourth vector is pointing left, labeled F Subscript f. The upward vector is the same length as the downward vector. The right vector is the same length as the left vector. A free body diagram with 3 force vectors. The first vector is pointing downward, labeled F Subscript g Baseline. The second vector is pointing right, labeled F Subscript p Baseline. The third vector is pointing upward, labeled F Subscript N Baseline. All three vectors are of equal length. A free body diagram with 4 force vectors. The first vector is pointing downward, labeled F Subscript g Baseline. The second vector is pointing right, labeled F Subscript f Baseline. The third vector is pointing upward, labeled F Subscript N Baseline. The fourth vector is pointing up to the left, labeled F Subscript P Baseline. A free body diagram with 4 force vectors. The first vector is pointing downward, labeled F Subscript g Baseline. The second vector is pointing left, labeled F Subscript f Baseline. The third vector is pointing upward, labeled F Subscript N Baseline. The fourth vector is pointing down to the right, labeled F Subscript P Baseline. All vectors are the same length.

Answer 1

The correct free body diagram for the broom would be the one with 3 force vectors which is the far right. Since we assume the floor is level, gravity, Fg, always operates downward, while normal, Fn, acts straight up in opposition to gravity.

However, the pushing force (Fp) and the friction force (Ff) are undoubtedly on your mind. Think about the direction of the applied force for the Fp. When the guy pushes the broom, the force is applied downward and to the right since the broom's head is on the ground and his arms are above and to the left.

Even when the broom isn't going down, force is still being delivered in that direction. Since friction always works against motion, the friction is to the left since the broom goes to the right.

The complete question with the diagram is attached.