The mass of a balloon with its contents is 1.5 kg. It is descending with an acceleration equal to half that of acceleration due to gravity. If it is to go up with the same acceleration keeping the volume same, its mass should be decreased by

Options

A. 1.2kg
B. 1kg
C. 0.75kg
D. 0.5kg

Answer

B

Explanation

Thrust acting on the ballon =` (mg)/2 =(1.5g)/2`
If 'x' kg of gas is removed from the ballon, from Archimedis principal
Force = Upthrust - Weight of the ballon
`(1.5 - x) g/2 = 1.5xx g/2- (1.5-x)g`
`therefore x=1`