the value of 0.36 was your example

the formula is in 1632.2

Fp = 4.0 * Ca * Ip * Wp (32-1)

or

Fp = ap*Ca*Ip/Rp*(1+3*hx/hr)*Wp (32-2)

replace with your applicable values and you obtain the horizontal acceleration (let's call "u")

Fp=u*Wp or u=Fp/Wp

so u=4.0 * Ca * Ip or u=ap*Ca*Ip/Rp*(1+3*hx/hr)