Each of three graphs represents acceleration versus time for an object that already has positive velocity at time t₁. Which graphs show speed increasing throughout t₁ to t₂?
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Question

Each of three graphs represents acceleration versus time for an object that already has positive velocity at time t₁. Which graphs show speed increasing throughout t₁ to t₂?

G1 Physics · Accepted Answer

The object already has positive velocity. Its speed increases throughout only if acceleration stays positive throughout the interval. In all three shown a-t graphs, acceleration remains above the time axis, so speed increases in I, II and III. Hence option D.