The increased use of smartphones in web survey responding did not only raise new research questions but also fostered new ways to research survey completion behavior. Smartphones have many built-in sensors, such as accelerometers that measure acceleration (i.e., the rate of change of velocity of an object over time). Sensor data establish new research opportunities by providing information about physical completion conditions that, for instance, can affect response quality. In this study, we explore three research questions: (1) To what extent do respondents accept to comply with motion instructions? (2) What variables affect the acceleration of smartphones? (3) Do different motion levels affect response quality? We conducted a smartphone web survey experiment using the Netquest opt-in panel in Spain and asked respondents to stand at a fix point or walk around while answering five single questions. The results reveal high compliance with motion instructions, with compliance being higher in the standing than in the walking condition. We also discovered that several variables, such as the presence of third parties, increase the acceleration of smartphones. However, the quality of responses to the five single questions did not differ significantly between the motion conditions, a finding that is in line with previous research. Our findings provide new insights into how compliance changes with motion tasks and suggest that the collection of acceleration data is a feasible and fruitful way to explore survey completion behavior. The findings also indicate that refined research on the connection between motion levels and response quality is necessary.