An object starts at position x = +10 meters. It moves at +5 m/s for 10 seconds then (instantly! magically!) changes its velocity to -10 m/s for the next 10 seconds.

Question

An object starts at position x = +10 meters. It moves at +5 m/s for 10 seconds then (instantly! magically!) changes its velocity to -10 m/s for the next 10 seconds.

An object starts at position x = +10 meters. It moves at +5 m/s for 10 seconds then (instantly! magically!) changes its velocity to -10 m/s for the next 10 seconds.

1. Draw a graph showing the object's position as a function of time.
2. Draw a graph showing the object's velocity as a function of time.
3. What is the object's displacement? Use a fact + connection to explain how you know the displacement.

Answer 1

1) x(0) = 10. The curve is linear with a slope of 5 m/s until 10s. At 10s, the slope is -10m/s for 10s.

2) v(0) = 5m/s. The curve is horizontal until 10s. At 10 seconds, the curve abruptly jumps to the value of -10 m/s and is horizontal at that value for 10 s.

3) The displacement is always final position - original position which you can pick off the x vs t graph.

On the velocity graph, you could take d = vt for each section and add them. Don't forget that the 2nd half displacement is negative because of the negative velocity.

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