The table below shows the motion of an automated warehouse robot. It carries a box along a straight aisle, waits while the box is removed, and then reverses...
Question 1 Report
The table below shows the motion of an automated warehouse robot. It carries a box along a straight aisle, waits while the box is removed, and then reverses. Distances are measured from its charging point. The accompanying diagram shows the aisle and the charging point.
| time / s | position from charging point / m |
|---|---|
| 0 | 0 |
| 10 | 20 |
| 20 | 40 |
| 30 | 40 |
| 40 | 20 |
(a) State the position of the robot at 30 s. [1]
(b) Which time interval shows that the robot is stationary? Give evidence from Table 1. [2]
(c) Calculate the average velocity of the robot from 0 s to 40 s. [3]
(d) Explain why the average speed for this journey is not zero. [3]
Answer Details
(a) At 30 s, the robot is 40 m from the charging point. [1]
(b) The robot is stationary from 20 s to 30 s. [1] Its position remains 40 m throughout this interval. [1]
(c) \[\text{displacement}=20-0=20\text{ m}\]
\[\text{average velocity}=\frac{20}{40}=0.50\text{ m/s}\]
The average velocity is 0.50 m/s away from the charging point. [3]
(d) The robot travels a non-zero total distance. [1] It moves away from the charger and then returns part way. [1] Average speed uses total distance divided by time, not displacement, so it is not zero. [1]
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