To determine how the acceleration will change when the net force is halved, we can use Newton's second law of motion, which states:
\[ F = m \cdot a \]
Where:
- \( F \) is the net force applied to an object,
- \( m \) is the mass of the object,
- \( a \) is the acceleration of the object.
In the first trial, when a net force of \( 0.7 , \text{N} \) is applied, we can express the acceleration as:
\[ a_1 = \frac{F_1}{m} = \frac{0.7 , \text{N}}{m} \]
In the second trial, if half of the net force is applied, the new force \( F_2 \) is:
\[ F_2 = \frac{0.7 , \text{N}}{2} = 0.35 , \text{N} \]
The new acceleration \( a_2 \) then becomes:
\[ a_2 = \frac{F_2}{m} = \frac{0.35 , \text{N}}{m} \]
Comparing the two accelerations:
\[ a_2 = \frac{0.35 , \text{N}}{m} = \frac{0.7 , \text{N}}{2m} = \frac{a_1}{2} \]
Thus, the acceleration in the second trial is half of its original value. Therefore, the correct answer is:
The acceleration is half of its original value.