Instantaneous speed from tangent to distance-time graph

Steps:

• Identify the tangent line to the curve at t=10s, which represents instantaneous velocity.
• Determine the slope of this tangent: rise (change in distance) over run (change in time).
• Measure the coordinates on the tangent line near 10s to compute Δd/Δt.
• The calculated slope equals 0.3 m/s, the speed at that instant.

Why A is correct:

• Speed is the gradient of the distance-time graph; the tangent's slope at 10s directly gives 0.3 m/s by definition.

Why the others are wrong:

• B: 0.8 m/s overestimates the tangent slope, possibly confusing with average speed over an interval.
• C: 1 m/s mismatches the graph's tangent gradient, ignoring the curve's local steepness.
• D: 3 m/s reflects a much steeper slope, like an initial or maximum rate, not at 10s.

Final answer: A