a parachutist jumps from an aeroplane.he has a mass of 80kg.initially,he 'free-falls',before his parachute opens.what is his initial acceleration

Answer 1

All free-falls on earth starts at g (9.8 m/s²) if initiated near the surface.

At high elevations, g is slightly reduced because of the greater distance from the centre of the earth.

Subsequently, as velocity is substantial, air-resistance plays an important rôle in reducing the acceleration until the terminal velocity is reached when the acceleration is zero.

Read about it at the following link, which includes interesting parachute jumps at the end of the article:
http://en.wikipedia.org/wiki/Free_fall