A solid sphere falls with a terminal velocity of 20 m s−1 in air. If it is allowed to fall in vacuum,
terminal velocity will be 20 m s−1
terminal velocity will be less than 20 m s−1
terminal velocity will be more than 20 m s−1
there will be no terminal velocity
In vacuum, no viscous force exists. The sphere therefore, will have constant acceleration because of gravity. An accelerated motion implies that it won't have uniform velocity throughout its motion. In other words, there will be no terminal velocity.