Is lambda a dimensionless quantity?

No

Explanation:

lambda represent wavelength

Lambda is a letter in the Greek alphabet. You need it to spell many words in Greek. Also, if you like, you can use it as a variable in an algebraic expression, or as a name for your cat, or to represent a physical or chemical quantity.

The quantity you use it to represent may or may not have dimensions or units of measurement.

force is mass*acceleration.

we have a very small mass: 11.4*0.001 kg

if we want 0.035n of force, we need an acceleration:

0.035 = 11.4*0.001*a

a = 0.035/(11.4*0.001) m/s^2

answer and explanation;