Question

What will be the acceleration of a skydiver
when air resistance builds up to 77% of her
weight? Assume the acceleration due to grav-
ity is 10 m/s2 .
Answer in units of m/s2

Answer 1

Hi,
I never have solved this type of question but .... let's give it a try

weight of a person = mass of a person * gravitational acceleration
= mg

If the mass of the sky diver is x kg
then his weight is = 10x N

Al right, Now that's the force that acts downwards when the skydiver is under free fall
But when there is air resistance, another force is created upwards against the skydiver which will retard his acceleration.

as given in the question they say that the air resistance is 77% of the skydiver's weight
which means that force is equal to
(77/100)*10x = 7.7x

So if I'm right, now there should be 2 forces acting on the skydiver
1. weight of the skydiver which is 10x N and which acts downward
2. Air resistance which is 7.7x and which acts upward

Hence both forces acts in opposite directions we can get the resultant force on the skydiver by
10x - 7.7x = 2.3x N

Which means now the skydiver is under a force which is 2.3x N in magnitude and which acts downwards.

According to Newtons second law;
F = ma
2.3 =xa
a = 2.3 m/s^2

I think it should be the answer and i'm about 97% sure about it :-)

Answer 2

Wow thanks that was right :)

Answer 3

u r welcome!