question_answer

Two bodies of masses M and m are allowed to fall from the same height. If the air-resistance be same for each body, will the two bodies reach the earth simultaneously?

Answer:

                No. Let the air-resistance on each body be F. Net downward force on body of mass M = Mg - F Acceleration of body of mass M, \[a=\frac{Mg-F}{M}=g-\frac{F}{M}\] Similarly acceleration of body of mass m, \[a'=g-\frac{F}{m}\] As \[M>m\]        \[\therefore \]  \[a>a'\] Thus the acceleration of the larger mass is greater, it will reach the earth earlier.