There are some toy gears on the front of the baby walker. Figure 6 shows the gears. The child applies a force to gear A, which causes a moment about the pivot. Write down the equation which links distance (d), force (F) and moment of a force (M).

The moment of a force (also known as torque) is a measure of its tendency to cause a body to rotate about a specific point or axis. It is calculated as the product of the force and the perpendicular distance from the pivot to the line of action of the force. The standard symbols are M for moment (measured in Newton-metres, Nm), F for force (in Newtons, N), and d for the perpendicular distance (in metres, m). The equation is: M = F × d.