$1($a$)$ Fig. $1\mathrm{.}1$ shows a sealed weather balloon which is stationary in still air.

State whether the overall density of the balloon and its instruments is greater than, less than,

or the same as the density of the surrounding air.

$($b$)$ At night, the gas inside the balloon cools. The pressure of the air outside the balloon remains

the same.

$($i$)$ State whether the balloon rises, falls or remains stationary.

$($c$)$ An object is released from the balloon. It starts at rest and eventually reaches a constant speed.

$($i$)$ On the axes of Fig. $1\mathrm{.}2,$ sketch a speed$-$time graph to show this motion.

Fig. $1\mathrm{.}2$

$($ii$)$ State the values of the initial acceleration and the final acceleration of the object.

initial acceleratinn

final acceleration