A hiker starts from camp (taken as origin) and walks straight along a trail as…

PHYSICS · Single correct · A Level · Physics · Mechanics and materials · Mechanics and materials

Problem

A hiker starts from camp (taken as origin) and walks straight along a trail as follows: • first 5 min5\,\text{min}: uniform speed, covering 300 m300\,\text{m} away from camp, • next 2 min2\,\text{min}: rests, • last 3 min3\,\text{min}: walks back 120 m120\,\text{m} toward camp at uniform speed. Which of the following best describes the displacement–time graph for the entire 10 min10\,\text{min} journey? (a) A straight line sloping upward from (0,0)(0,0) to (5 min,300 m)(5\,\text{min},300\,\text{m}), followed immediately by a straight line sloping downward to (10 min,180 m)(10\,\text{min},180\,\text{m}). (No horizontal segment) (b) A straight line sloping upward from (0,0)(0,0) to (5 min,300 m)(5\,\text{min},300\,\text{m}), a horizontal line up to 7 min7\,\text{min}, then a straight line sloping further upward to (10 min,420 m)(10\,\text{min},420\,\text{m}). (c) A straight line sloping upward from (0,0)(0,0) to (5 min,300 m)(5\,\text{min},300\,\text{m}), a horizontal line up to 7 min7\,\text{min}, then a straight line sloping downward to (10 min,180 m)(10\,\text{min},180\,\text{m}). (d) A straight line sloping upward from (0,0)(0,0) to (5 min,300 m)(5\,\text{min},300\,\text{m}), a horizontal line up to 7 min7\,\text{min}, then a straight line sloping downward to (10 min,0)(10\,\text{min},0).

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