Question

A situation were you can accelerate even though your speed doesn't change

Answer 1

Step-by-step explanation:

airplane flying around in a circle

Answer 2

'Acceleration' doesn't mean 'speeding up'. It means any change in the speed or direction of motion. Any motion that's not constant speed in a straight line is accelerated motion.
Here are a few. I'm sure you can think of lots more.

-- go around a curve on a bicycle or in a car
-- jump up in the air and come down again
-- jump from a diving board
-- stop pedaling or turn off the engine and coast to a stop
-- ride a satellite in orbit around the Earth
-- stand still on the Earth, and let it spin you around in a circle in 24 hours