Question

which of these would be a part of a force diagram for this image? choose three correct answers. a vector labeled $f_g$ pointing straight down; a vector labeled $f_g$ pointing parallel to and down the ramp; a vector labeled $f_n$ pointing straight up, directly opposite $f_g$; a vector labeled $f_{fric}$ pointing parallel to and up the ramp

Explanation:

1. For a block on an inclined plane, the gravitational force component \( F_g \) (or \( F_{gy} \) for the vertical component) points straight down (correct as gravity acts vertically downward).
2. The parallel component of gravity \( F_{gp} \) (or \( F_p \)) points parallel to and down the ramp (this is the component causing the block to slide down, so this vector should be included).
3. The normal force \( F_N \) acts perpendicular to the ramp, not straight up opposite gravity (so this is incorrect).
4. Friction \( F_{fric} \) (if present, assuming the block might be moving or at rest) acts parallel to the ramp and up the ramp (opposing the downward parallel component of gravity, so this is correct). Wait, but the first selected option: Wait, let's re - analyze. The first option: "a vector labeled \( F_g \) (assuming \( F_{gy} \)) pointing straight down" is correct (gravity is vertical). The second option: "a vector labeled \( F_p \) pointing parallel to and down the ramp" is correct (parallel component of gravity). The fourth option: "a vector labeled \( F_{fric} \) pointing parallel to and up the ramp" is correct (friction opposes motion, so if the block is sliding down or tending to slide down, friction is up the ramp). The third option is wrong because normal force is perpendicular to the ramp, not vertical. So the correct ones are:

• a vector labeled \( F_g \) (or \( F_{gy} \)) pointing straight down
• a vector labeled \( F_p \) pointing parallel to and down the ramp
• a vector labeled \( F_{fric} \) pointing parallel to and up the ramp

Answer:

• a vector labeled \( F_g \) (or \( F_{gy} \)) pointing straight down
• a vector labeled \( F_p \) pointing parallel to and down the ramp
• a vector labeled \( F_{fric} \) pointing parallel to and up the ramp