In the context of a graph plotting force (y-axis) versus acceleration (x-axis) for several motorboats with the same mass, the relationship is governed by Newton's second law, which states that \( F = ma \).
In the equation \( F = ma \):
- \( F \) is the force (in Newtons),
- \( m \) is the mass (in kilograms),
- \( a \) is the acceleration (in m/s²).
When plotted as Force (y) against Acceleration (x), the equation can be rearranged as:
\[ F = m \cdot a \]
This will yield a straight line graph with:
- a slope equal to the mass \( m \),
- and a y-intercept of 0 when \( a \) is 0 (since if there's no acceleration, there’s no force being applied).
Therefore, the y-intercept of this graph is zero.