A 4.0-kg block slides down a frictionless ramp inclined at 30° to the horizontal. What is the magnitude of the block’s acceleration along the ramp? Use g = 9.8 m/s².
A2.0 m/s²
B4.9 m/s²
C8.5 m/s²
D9.8 m/s²
Explanation
📌 On a frictionless incline, acceleration along the ramp = g·sin θ = 9.8 × sin(30°) = 9.8 × 0.5 = 4.9 m/s². Mass cancels — same rate for any object at same angle. Distractor A unnecessarily divided by mass; C used cos(30°) instead of sin(30°) — the sin/cos swap; D used full g without decomposition.