Question

A,horizontial,force,of,40N,actingon,a,block,of,frictionless,level,surface,produces,an,acceleration,of,2.5m/s^2.A,second,block,with,a,mass,of,4.0kg,is,dropped,onto,the,first,.What,is,the,magnitude,of,acceleration,of,the,combination,of,blocks,if,the,same,force,continues,to,act?,(assume,that,the,second,block,does,not,slide,on,the,first,block.)

Answer 1

Would it be asking to much for you to use spaces instead of commas between words?

Get the mass M1 of the first block from
F = 40 N = M1* 2.5 m/s^2
M1 = 16 kg
Dropping the second block on top increases total mass to 20 kg.
With the same force acting, acceleration is reduced by a factor 16/20 = 0.8