Suspense is used to create drama throughout a film as well as foreshadow future events which will happen further on down the line.
For a thriller opening it helps build up the tension from the start creating an uneasy atmosphere which increases the viewers heart rate using visceral effect which is an affect on the human body. This also could indicate the viewers to scream in terror or shock.
Suspense is used to keep the audience interested and locked into whatever they are watching as it provides a lot of things which go unanswered. this makes the audience desperate to know what is going on.
'The Bomb Theory' is given off using suspense since in some cases the audience may know more that the characters on screen allowing which enables them to be on the edge of their seat.
Suspense can also be created through the false plateau which comes before the real and lulls the audience into a false sense of security. for example, in jaws two children were used to create suspension by having a cardboard fin and swimming through the water making everyone think they were a shark and making the audiences heart race increase for no reason. Then the scene with a real shark attack follows which makes the whole thing even more scarier as the audience had become relaxed and wasn't expecting it. This makes it even more dramatic.