Net force zero for constant speed uphill

Steps:

• Resolve forces parallel to slope: gravitational component mg sin θ acts down the slope.
• Resistive force F also acts down the slope, opposing uphill motion.
• Let P be propelling force up the slope; for constant speed, net force = 0, so P - mg sin θ - F = 0.
• Solve: P = mg sin θ + F.

Why C is correct:

• Newton's first law requires propelling force to balance total opposing forces (gravity component + resistance) for zero acceleration.

Why the others are wrong:

• A: Ignores resistive force F, underestimating total opposition.
• B: mg cos θ is normal (perpendicular) force; adding F doesn't address parallel propulsion.
• D: mg cos θ is irrelevant perpendicular component; subtracting F yields incorrect imbalance.

Final answer: C