[amp_mcq option1=”01:05″ option2=”01:02.5″ option3=”01:25″ option4=”01:50″ correct=”option3″]
The correct answer is $\boxed{\text{A. }1:5}$.
The model scale is the ratio of the prototype’s dimensions to the model’s dimensions. In this case, the prototype is expected to attain a velocity of 5 m/sec, while the model is tested at a velocity of 25 m/sec. This means that the model is 5 times smaller than the prototype. Therefore, the model scale is 1:5.
Option B is incorrect because the model is 5 times smaller than the prototype, not 2.5 times smaller.
Option C is incorrect because the model is 5 times smaller than the prototype, not 25 times smaller.
Option D is incorrect because the model is 5 times smaller than the prototype, not 50 times smaller.