What class of lever system do the following activities describe? a. The soleus muscle plantar flexes the foot. b. The triceps brachii is strained while doing pushups.

Video transcript

Hi everyone. Let's take a look at this practice problem together. Now, before we begin, just a warning that this video is longer than most. It requires a review of a lot of information in a short amount of time. However, stay in this with me. And by the end you should have a clearer understanding of lover classes. So our practice problem is statement. A, the bicep curl is an example of a class three lever system where the effort generated by the bicep muscle is situated between the fulcrum, the elbow joint and the load, the weight being lifted. Statement B A full body push up is an example of a class one lever system where the fulcrum is situated between the effort the force applied to the door and the load, the weight of the door. Select the appropriate choice. Option A statement A is incorrect statement B is correct. Option B statement A is correct statement B is incorrect. Option C both statements are correct and option D both statements are incorrect. OK. So to begin talking about this problem, recall that there are three parts to a lever. So let's review those, the three parts are the fulcrum, the effort and the load. Now the fulcrum is fixed, it does not move. The effort is the force that is applied to the lever and the load is the part that gets moved. So in our bodies, the fulcrum are joints, the effort is the muscle contraction and the load is when the bone mobs also recall that there are different types of lever classes. And on the screen, I am going to put up a table to help us sum summarize each of the lever classes and we'll review that information together. Let me go ahead and get this drawing up on the screen. Now, for lever classes, it's important to note the order and the location of the lever parts because that helps to define the different class types. So for class one lovers, the fulcrum is always in the middle. An example of a class one lever is a seesaw. So this seesaw is a plank with the load on one side of the plank and the effort on the other side, the fulcrum is located in the middle for class two levers. It's the load that is in the middle. An example of this type is a wheelbarrow. The effort is applied when the handle is lifted, the load is the weight in the wheelbarrow and the fulcrum is the will. This type of liver isn't common in the body. Lastly, there's the class three levers for this type. Effort is always in the middle. An example is a broom. The handle where our hands hold the handle is the fulcrum. The effort is the middle of the handle and the load is the bristles. Now class three is the most common class type of levers found in our bodies. Now let's talk about the examples given in statement A and B and let's remember what those are. So statement A was that a bicep curl is a class three lever system. Statement B is that a full body push up is a class one lever system. So for statement A is a bicep curl, A class three lever. So on the screen, I am putting up a drawing of a bicep curl so that we can talk about its lover type. So this is the drawing of the bicep curl. Now in the bicep curl, the full Crum is the elbow joint. The effort is the bicep muscle contraction and that pulls on the radius bone and the load is the weight that is lifted. So which lever part is in the middle? It's the effort. That means that statement A is correct. A bicep curl is a class three lover system. Now for statement B is a push up a class one lever on the screen. I am putting up a drawing of a push up in a push up. The full crumb is the ankle joint. The load is the whole body weight and the effort is done by the arm and chest muscles. Now, since it's the load that is in the middle, A push up is a class two lever system. That means that statement A was correct and statement B is incorrect. Statement B A push up is a class two lever system. The correct answer to this question therefore, is option B statement A is correct and statement B is incorrect. All right, everyone. Thanks for sticking with me. I hope you found this helpful and I'll see you soon for the next practice problem.