code: private boolean isAccelerating(SensorEvent event) {
  		float ax = event.values[0];
  		float ay = event.values[1];
  		float az = event.values[2];
  
  		final double magnitude = Math.sqrt(ax * ax + ay * ay + az * az);
  		return magnitude > ACCELERATION_THRESHOLD;
  	}
docs: Returns true if the device is currently accelerating.