To determine the acceleration of the wooden block when it hits the sensor, we start by utilizing the formula related to Newton's Second Law of Motion, which is represented by:
[tex]\[ F = m \times a \][/tex]
Here:
- [tex]\( F \)[/tex] is the force,
- [tex]\( m \)[/tex] is the mass, and
- [tex]\( a \)[/tex] is the acceleration.
In this problem:
- [tex]\( F = 4.9 \)[/tex] newtons,
- [tex]\( m = 0.5 \)[/tex] kilograms.
We need to solve for the acceleration [tex]\( a \)[/tex]. Rearranging the formula to solve for [tex]\( a \)[/tex] gives us:
[tex]\[ a = \frac{F}{m} \][/tex]
Substituting the given values into the equation:
[tex]\[ a = \frac{4.9 \, \text{N}}{0.5 \, \text{kg}} \][/tex]
Now, we perform the division:
[tex]\[ a = 9.8 \, \text{m/s}^2 \][/tex]
Therefore, the acceleration of the wooden block when it hits the sensor is:
[tex]\[ \boxed{9.8 \, \text{m/s}^2} \][/tex]
The correct answer is [tex]\( \text{D} \, 9.8 \, \text{m/s}^2 \)[/tex].