The Solution:
We are required to find the force.
![\begin{gathered} F\propto a \\ \text{This implies that:} \\ F=ka \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/3uedlynwf4guufc11z9w80qug36jgsyp4i.png)
In this case,
F= force=30 N
a = acceleration = 3m/s
k = constant of proportionality = ?
We shall find the constant k by substituting the above values in the formula.
![\begin{gathered} F=ka \\ 30=k(10) \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/6bxodkn2ddj2eaoac5k8wgi09xss76uc5g.png)
Dividing both sides by 10, we get
![k=(30)/(10)=3](https://img.qammunity.org/2023/formulas/mathematics/college/evcnqe2yapklffob3kmea9hsf344yqfsgm.png)
So,
The formula for finding Force is:
![F=3a](https://img.qammunity.org/2023/formulas/mathematics/college/77ba0bwfzdnke8rjcvzldblggq84rbarpx.png)
To find the Force when a = 3m/s, we shall substitute 3 for a in the formula.
![F=3*3=9N](https://img.qammunity.org/2023/formulas/mathematics/college/jbokigd7vy4hh8oo8i03r7jlbz3xv2tc5r.png)
Therefore, the correct answer is 9 N