Question

describing a force diagram
a vector labeled $f_g$ pointing straight down
a vector labeled $f_p$ pointing parallel to and down the ramp
a vector labeled $f_n$ pointing straight up directly opposite $f_g$
a vector labeled $f_{fr}$ pointing parallel to and up the ramp
a dot that represents the box

Explanation:

To describe the force diagram for a box on a ramp, we analyze each option:

1. \( F_g \) (gravity): Gravity acts straight down, so "a vector labeled \( F_g \) pointing straight down" is correct.
2. \( F_p \) (parallel component of gravity): The component of gravity parallel to the ramp acts down the ramp, so "a vector labeled \( F_p \) pointing parallel to and down the ramp" is correct.
3. \( F_N \) (normal force): Normal force acts perpendicular to the ramp (not straight up opposite \( F_g \) unless on a horizontal surface), so this is incorrect.
4. \( F_f \) (friction): If the box is sliding or has a tendency to slide down, friction acts up the ramp parallel to it, so "a vector labeled \( F_f \) pointing parallel to and up the ramp" is correct.
5. Dot for the box: A free - body diagram uses a dot to represent the object (the box), so "a dot that represents the box" is correct.

Answer:

• A vector labeled \( F_g \) pointing straight down (checked)
• A vector labeled \( F_p \) pointing parallel to and down the ramp (checked)
• A vector labeled \( F_f \) pointing parallel to and up the ramp (checked)
• A dot that represents the box (checked)
• A vector labeled \( F_N \) pointing straight up, directly opposite \( F_g \) (un - checked)