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# MCAT Physics: A Brief Introduction to Work and Energy Photo by Jonny Kennaugh on Unsplash

Depending on your interest in this topic, initially seeing this throughout your MCAT practice would either have made your heart sink or have you jumping with immense joy. For most, there will definitely be some confusion.

Although it may not be immediately clear why Physics is incorporated into the MCAT, learning about this subject will greatly support your role as a future medical practitioner. Not only does Physics (similarly to Chemistry) help you understand the world and processes around you, but some medical procedures simply cannot be understood without a sufficient grasp of knowledge of Physics concepts. For example, fluid dynamics, a sector of physics, is important for a cardiologist to know very well because the concepts of the subtopic directly relate to the functions of the circulatory system.

But where should you start? Admittedly, there are so many subtopics that fall under Physics, so this section may be a bit overwhelming and difficult to start studying for. To best solve this dilemma, you may want to turn to the subtopics commonly seen in an Introduction to Physics course.

One of the topics that are introduced very early on in one’s prerequisite physics courses is Work and Energy. Since physics revolves around understanding how both matter and energy coexist, knowing how these components can alter movement or change in the environment is critical in understanding other Physics topics. In addition, distinguishing the types of forces and interactions that could occur in myriads of situations is exactly what is necessary to be a skilled medical practitioner in the medical field. Grasping these constant instances of interactions helps aid with your critical thinking, logic, and understanding of your own surroundings.

Whether this may be a refresher or introduction to Work and Energy, here are some key basic takeaways that you must gain from this subtopic:

• Work is the force that allows the object to be moved or displaced. To find the measure of work done on an object, one would need to utilize the following equation, where F represents the force of the object, d represents the displacement of the object, and cos(theta) represents the angle that could be distinguished between the displacement and the force:

W = F x d x cos(theta)

• Potential energy can be characterized by the energy of the object based on its position. This energy may also be more commonly known as a “stored energy”. However, there are a variety of forms of gravitational energy. The ones which are most common and will likely be in your MCAT examination include gravitational potential energy and elastic potential energy.

• Kinetic energy is depicted as a type of energy expressed by motion. Although there is vibrational, rotational, and translational kinetic energy, the general basis of kinetic energy is only dependent on the magnitude and speed of the object.

• Mechanical energy may appear as its own separate entity, but it merely acts as a placeholder for the aforementioned energy options. For example, if there is a tetherball pole with a ball hanging from a rope, one can say that the ball possesses mechanical energy in the form of gravitational potential energy (or whichever energy is most relevant to the scenario).

After reading those core concepts, do you feel adequately prepared for this portion of the MCAT? Were they familiar to you, or may this be a section that you need to focus on? If you feel confident about this section, you can start your review with the following questions below! Please note that you can find questions like these and more through online MCAT practice websites, Quizlet, and more.

1. After a cannonball is fired into friction-less space, the amount of force needed to keep it going equals

a. zero, since no force is necessary to keep it moving.

b. twice the force with which it was fired.

c. one half the force with which it was fired.

d. the same amount of force with which it was fired.

2. A ball drops some distance and gains 30 J of kinetic energy. Do not ignore air resistance. How much gravitational potential energy did the ball lose?

a. more than 30 J

b. exactly 30 J

c. less than 30 J

d. cannot be determined from the information given

3. A 0.200 kg mass attached to the end of a spring causes it to stretch 5.0 cm. If another 0.200 kg mass is added to the spring, the potential energy of the spring will be

a. the same

b. twice as much

c. 8 times as much

d. 4 times as much

4. A set of pulleys lifts a piano and does 3,356 joules of work. If the piano is lifted in 75 seconds, how much power is used?

a. 40.75W

b. 42.75W

c. 48.75W

d. 44.75W

5. A woman exerts a constant horizontal force pulling a box across a rough floor at a constant speed. What can you say about the work done by friction?

a. Friction does positive work.

b. Friction does negative work.

c. Friction does not do any work (0).

d. There is not enough information to answer this question.

Answer Key: 1A ,2A,3D, 4D, 5B

Thank you so much for reading! I wish you all the best of luck in your MCAT and medical school endeavors!

- Ashlyn Southerland

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Pomeroy, R. (2013, April 29). Do Doctors Need Physics? https://www.realclearscience.com/blog/2013/04/do-doctors-need-physics.html

The Physics Classroom. (n.d.). Definition and Mathematics of Work and Energy. https://www.physicsclassroom.com/class/energy/Lesson-1/Definition-and-Mathematics-of-Work

The Physics Classroom. (n.d.). Kinetic Energy. https://www.physicsclassroom.com/class/energy/Lesson-1/Kinetic-Energy

The Physics Classroom. (n.d.). Mechanical Energy. https://www.physicsclassroom.com/class/energy/Lesson-1/Mechanical-Energy

The Physics Classroom. (n.d.). Potential Energy. https://www.physicsclassroom.com/class/energy/Lesson-1/Potential-Energy

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