Two model trains are propelled along a straight, frictionless track by electric motors. Train X has a total mass of 100g and is moving at speed v. Train Y has a total mass of 10g and is moving at speed 3v. The ratio of the kinetic energies of Train X to Train Y is:
A. 10:9
B. 9:10
C. 10:3
D. 1:9
Click for Explanation
The kinetic energy equation is Ekinetic = ½ mv2. We can plug in the values given and set up a ratio to answer the question.
EX = ½ (100)(v)2
EY = ½ (10)(3v)2 = ½ (10)(9v2)
EX / EY = ½ (100)(v)2 / ½ (10)9v2
EX / EY = (100)(v)2 / (10)9v2
EX / EY = (10)(v)2 / 9v2
EX / EY = 10 / 9
Thus choice (A), 10:9 is the correct answer.
Want more MCAT practice?
We’ve got options for every schedule and learning style!
From the best online MCAT course created by top instructors with 524+ MCAT scores to the most representative full-length practice exams and private tutoring, we can custom tailor your MCAT prep to your goals!
Not sure which option is right for you? Schedule a free MCAT consultation with an MCAT expert using the form below. No obligation, just expert advice.
