(concurrring specially).
I concur in the result. I .cannot agree, however, that the trial court did not abuse its discretion in overruling the objection to the admission of the expert opinion as to the speed of defendant’s automobile as based on the conservation of momentum theory. Generally speaking, all computations under this theory are based upon the movements and the ultimate positions of the two cars after the impact and upon the weights of each vehicle. The expert’s opinion was based on assumed facts which were wholly inadequate and could provide only a foundation for speculation. Both vehicles were moving immediately before the impact. The expert witness purported to give an opinion of the speed of one vehicle without knowing the speed of the other, without knowing the condition of the tires on the vehicles, without knowing whether the road surface was wet or dry, and without giving any consideration to the voluntary or involuntary action, or inaction, of the decedent in applying the brakes on the truck.8 It is difficult to apply the law of physics with any accuracy when the operative facts are rendered uncertain by the element of human intervention. The surrounding facts and circumstances immediately preceding a collision are complicated and are difficult to adequately describe, and this is especially true when they are affected or modified by the uncertain element of human intervention. Where an expert’s opinion, involving an application of the laws of physics, rests *446on inadequate or uncertain facts, its basic inaccuracy is likely to mislead the jury and it should not be admitted in evidence. Although the trial court erred in not excluding the expert’s opinion, no prejudice resulted since there was ample evidence to sustain a finding that the defendant traveled at an excessive speed.
See, Romann v. Bender, 190 Minn. 419, 424, 252 N. W. 80, 82.