The characteristic that will be affected by increasing the speed of an object from 30 meters per second (m/s) to 40 meters per second (m/s) is kinetic energy.
Kinetic energy is calculated using the formula:
\[ KE = \frac{1}{2} mv^2 \]
where \( m \) is the mass of the object and \( v \) is its velocity. Since the speed (velocity) is increasing, the kinetic energy will also increase.
The other options listed (weight, gravitational attraction, mass) would not change just by changing the speed of the object.