Answer:

Explanation:
Given
Force directly proportional to acceleration
Force = 21N when Acceleraion = 7m/s^2
Required
Determine the force when acceleration = 9m/s^2
The variation between force (F) and acceleration (A) implies that:

Convert to an equation

Where m is constant.
When F = 21 and A = 7, we have:

Solve for m


When A = 9
Substitute 9 for A and 3 for m in


