F the same net force is applied to a 7 kg object and a 21 kg object, then the A - 21 kg object accelerates three times faster than the 7 kg object. B - the 7 kg object accelerates three times faster than the 21 kg object. C - both objects accelerate at the same rate because the force is the same. D - neither object will accelerate because there is a net force on the objects.

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