Question

A parachute of mass m starts coming down with a constant acceleration a. Determine the ballast mass to be released for the parachute to have an upward acceleration of same magnitude. Neglect air drag.

• A. $\frac { 2 m a } { a + g }$
• B. $\frac { \mathrm { ma } } { \mathrm { a } - \mathrm { g } }$
• C. $\frac { \mathrm { ma } } { \mathrm { a } + \mathrm { g } }$
• D. $\frac { 2 m a } { a - g }$

Answer 1

Answer: (A)

$\frac { 2 m a } { a + g }$

Answer 2

If T is the upward thrust on parachute, then

ma = mg – T ……… (i)

Let m' be the mass to be released, then

T – (m – m')g = (m – m')a ………. (ii)

Adding (i) and (ii)

m'g = 2ma - m'

or m' = $\frac { 2 m a } { a + g }$