Respuesta :
Answer;
B- the 7 kg object accelerates three times faster than the 21 kg object
Explanation;
From second Newton's law of motion;
F = ma , where F is the resultant force, m is the mass and a acceleration
In this case; if F is the same for 7 kg and 21 kg object then acceleration will be;
F = ma ; a = F/7
For 21 kg ;
F = 21 a ; a = F/21
Therefore; the 7 kg object accelerates three times faster than the 21 kg object