i need help on something, please answer fast =/

i started making a game and i need to make an event,
when i press to one of the sides (right, left, up, down)
it will start with velocity of 20 and grow to 10 velocity,
can someone help me please?
when i press to one of the sides (right, left, up, down)
it will start with velocity of 20 and grow to 10 velocity,
can someone help me please?