how can a speed be abstract noun..........as it can be calculated and read on speedometer
see, whenever you have a problem with types of nouns just ask whether you can touch it or not.
if you cant, it is an abstract noun.
these nouns can be felt.
for example you are sitting in a ride, you shout and yell as you are going very fast. so you can feel the speed with which you are going.
so, speed is an abstract noun.
hope it helps!!