As we know that if a rock is sliding under the influence of some external force then By Newton's II law we have
[tex]F = ma[/tex]
now we will have
[tex]a = \frac{F}{m}[/tex]
now we know that if force remains constant while we tripled the mass of the block then
new acceleration of the block will be given as
[tex]a' = \frac{F}{3m}[/tex]
so here the acceleration of the block will be decreased by 3 times
