A car accelerates uniformly from rest to 25 m/s in 10 seconds, then travels at constant speed for 20 seconds, and finally brakes uniformly to a stop in 5 seconds. What is the total distance traveled?
Answer and explanation
Correct answer: B. 687.5 m
- Step 1: Phase 1 (acceleration): d_1 = (1/2) v t_1 = 0.5 25 10 = 125 m.
- Step 2: Phase 2 (constant velocity): d_2 = v t_2 = 25 20 = 500 m.
- Step 3: Phase 3 (deceleration): d_3 = (1/2) v t_3 = 0.5 25 5 = 62.5 m.
- Step 4: Total distance: d = d_1 + d_2 + d_3 = 125 + 500 + 62.5 = 687.5 m.
Answer
687.5 m.
Why not the others: 625.0 m omits the braking phase distance; 750.0 m assumes constant speed during acceleration and braking; 500.0 m accounts only for the middle constant-speed phase.
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