Exam three

Question 1

define and explain kinetic and potential energy

Answer 1

kinetic energy-energy due to motion
potential energy-energy due to position (further from the earth, more pe)
strain PE-due to deformation (spring stretching)
gravitational PE- energy due to an objects position relative to earth

Question 2

explain how KE, PE, COM and base of support relate to whole body balance/stability. Provide an example.

Answer 2

Tall person has a high potential energy and cOM is further from the earth so the stability is based on base of support (means taller people generally have bigger feet) Relationship between COM and its magnitude and base of support. If an object moves outside its base of support, it will fall.

Question 3

explain the mechanical relationship of a linear muscle force to muscle torque

Answer 3

moment arm (moment arms shorten during every movement) during ROM some muscles are advantaged and some are disadvantaged because of moment arm lengths. As moment arm gets smaller, muscle is disadvantaged. Eccentric forces that cause force couples which means it will cause translation and rotation (create torque)

Question 4

what does sum of torque=0 and sum of torque does not equal 0 mean? what does sum of torque does not equal 0 mean with regard to synovial joint stability

Answer 4

sum of torque=0 means no rotation, the torques acting on the system are balanced. Either neither are active or the measures are equal. Sum of torque does not equal 0 means that one has advantage over the other (internal or external) When torques are unequal (force couples are unequal) sum of torque not equal to 0 means that translation and rotation are occurring and the joint is stable because of the ligaments that constrain translation.

Question 5

what is the impulse momentum equation? select a sports motion and provide a clear example of how impulse is being generated and clearly explain the change of momentum it is causing.

Answer 5

Impulse is applying a force over time. F(t)=m(Vf-Vi). Hitting a baseball: the more time given to create cross bridges, the more force produced. So, in other words, you want appropriate technique because it allows more time for the athlete to produce force. You can use impulse to increase or decrease momentum. Good technique increases time to increase impulse to cause a greater change in momentum.

Question 6

describe mechanical work and power. How is work related to power. Provide a real life example to illustrate how work and power may be used to better understand their value to biomechanics

Answer 6

work=f*displacement (sprinters com going 10m)
power=rate of work done (compare two people of different masses) essentially power allows you to equate different athletes with different statures.

Question 7

choose a sport that uses a club, racket, stick, or other instrument to strike or throw a ball/object. Within this context, what is “effective radius and why is it important to athletic performance. explain how Vt=wr can be manipulated in an example.

Answer 7

softball player with bat. Effective radius is the length of the arm and bat together as well as the technique that’s used. It’s important because you increase the distance between the axis of rotation and point of contact. Also, the faster the object rotates (w or angular velocity) the greater linear velocity.

Question 8

explain how the body and equipment can interact to increase performance with respect to Vt=wr. Be very specific in your answer as to the anatomy and or equipment being utilized.

Answer 8

Batting. Don’t extend arms until the right moment for extension. So you spin fast, keep things close, and then you release to be a long lever.

Question 9

using a throwing or kicking motion, explain how the athlete can manipulate their individual segment com and moment of inertias (H=I*w) to affect performance.

Answer 9

moment of inertia-the tighter, closer the distribution of mass to axis of rotation, the less inertia of that rotating body. Small amount of inertia=rotate quicker.
w (angular velocity) =the farther the point from the axis of rotation=greater angular velocity

Question 10

how do the equations (H=iw) and (Vt=wr) relate to each other in comparing equipment such as bats, clubs, and hockey sticks.

Answer 10

I=m*r^2 cant increase length without changing mass. If W changes, velocity changes
changing one factor affects the other equation
W=angular velocity-how quickly something is moving at an angle
radius is a part of the inertia and mass and if i want to increase effective radius then my mass and inertia and w will all change.