Any transparent surface in practical is neither a perfect absorber of electromagnetic waves neither a perfect reflector. Generally all the transparent surfaces reflect some amount of irradiation and the other parts are absorbed and transmitted.
<u>That is given by as relation:</u>
where:
absorptivity which is defined as the ratio of the absorbed radiation to the total irradiation
reflectivity is defined as the ratio of reflected radiation to the total irradiation
transmittivity is defined as the ratio of total transmitted radiation to the total irradiation
Newtons law states F=ma so F/m=a in addition it makes logical sense the lighter an object the easier it is to accelerate its velocity form 0 to some quantity