Question

If you take a tennis ball with 50 N force and kick a soccer ball with 50 N force, explain the difference in their motion according to Newton’s second law

Answer 1

Answer:

The smaller ball (the tennis ball) will receive a much larger acceleration than the soccer ball of larger mass.

Explanation:

According to Newton's 2nd Law of motion, $F=m*a$ (force equals mass times the acceleration imparted)

Since in this case we have the same force (50 N) applied to two different masses (one the tennis ball "m" which has smaller mass than the soccer ball of mass "M"), then the resultant accelerations will be different being the acceleration of the tennis ball  ($a_t$) much larger than the acceleration imparted to the soccer ball ($a_s$), as can be seen from solving for the acceleration in the previous equation:

$F=mass*a\\a=\frac{F}{mass} \\a_t=\frac{F}{m} =\frac{10N}{m} \\a_s=\frac{F}{M} =\frac{10N}{M}$

Notice than when calculating the acceleration of the tennis ball  ($a_t$), we divide 10N by a smaller number (m), than when we calculate the acceleration of the soccer ball ($a_s$), when we divide by a large number (M) resulting in a smaller quotient.