discussion with teachers

G field strength & potential
- please add a button to reveal and hide the g field strength and potential value bars
- make colour change of g field value bar to reflect +ve and -ve values.
- make -ve sign more visible if possible
- dotted lines to trace the test mass to graphs (g field & potential) and to vertical axis
- analysis tool to reveal the gradient of tangent to potential graph and g field strength

this are to do