LABORATORY REPORT Activity 2: Twitch Contractions and Summation PREDICTIONS Effect of Muscle Fiber Length on Contraction 1. As muscle fiber length increases: contraction force increases, becoming maximum at an optimal length, then decreasing at longer lengths. Effect of Stimulation Frequency on Contraction 2. As the frequency of stimulation increases, the force of contraction: increases. MATERIALS AND METHODS Measurement of Threshold Stimulus 1. Dependent Variable: contraction force. 2. Independent Variable: stimulation voltage 3. Controlled Variables: temperature, frequency of stimulation and muscle fiber length. Effect of Muscle Length on Contraction 1. Dependent Variable: contraction force. 2. Independent Variable: 60 Hz. 10. What was the maximum force generated in this experiment? 0.277 gf 11. How does increasing stimulation frequency affect force production? The tension produced during a sustained contraction is greater than that produced by a single twitch. The more stimuli per second, the greater the force generated by the muscle due to a
9. Record results of second experiment in log book. Variables My dependant variables are the amount of force which is shown by how far I pull back
5. Use a protractor to measure 30° from the equilibrium. Release the pendulum at this angle.
The passive force increases. 2. What happens to the active force as the muscle length is increased from 50mm to 100mm?
10. How does varying the frequency effect contraction force? Which interval caused the greatest contraction?
than they would at their natural length. This means that the muscle fibers will generate less tension with each
First, we will set up the force table. The table comes in three separate pieces the base, stand and table once we connect and fasten all three parts we must use a circular level to make sure the table is balanced. If the force table isn’t balanced then we must adjust the base’s feet to the appropriate levels on each leg till the bubble on the level is centered. We must then assign where the positive & negative x, y axis are on the force table as a point of reference and label them with tape .Then for part I we must apply 1.96 N in the positive x – direction, and 2.94 N in the positive y-direction then we must balance the two with a third force and record the magnitude and direction of it and a draw a diagram showing all three forces. Part II
The average rate of change is an average slope from the initial point to the final point. We would have to use A(x)=f(x)-f(a) divided by x-a to find the average rate of change. Sometimes we would want to know what the average rate of change is in the middle of the graph. The average rate of change is used in page 10, “How many more people?.” The concept of slope comes from the idea of a constant rate of change. To find the slope, you have to calculate y1-y2 divided by x1-x2. Slope is often denoted by the letter “m” which means that m+ equals the slope. Its problem is being used in page 21, “Rates, Graph, Slopes, and Equations.” Y=mx+b is the equation of the line that you can find using the two points. Variable “m” is the slope and “b” is the y-intercept.
Chapter 9 & 10 Short Answer and Critical Thinking CHAPTER 9 Short answer 15. Name and describe the four functional abilities of muscle that are the basis for muscle response. Contractibility- is the ability to shorten forcibly when adequately stimulated. This ability sets muscle apart from other tissue types. Extensibility- is the ability to
During an eccentric contraction, the muscle lengthens under tension due to an opposing force that is greater than the force being produced by the muscle (Lindstedt et al. 2001). Eccentric contractions require little metabolic energy, however they are characterized by a high production of force (Semmler 2014). Fick observed that a lengthening muscle contraction could exert more force than a shortening muscle contraction, while Hill later observed that the body has a lower energy demand when contracting eccentrically compared to concentrically (Lindstedt et al. 2001). When the force applied is larger than the force that is created, work is done on the lengthened muscle and mechanical energy is absorbed – this is called “negative work” (Lindstedt et al. 2001). This absorbed energy can either be dissipated as heat, or it can be temporarily stored as elastic recoil potential energy for later use (Lindstedt et al. 2001).
a. the gravitational force on the pendulum increases. b. the kinetic energy of the pendulum increases. c. the gravitational potential energy of the pendulum remains the same. d. the gravitational potential energy of the pendulum increases. In the diagram below, an ideal pendulum released from point A swings freely through point B.
4. Results: Following tables and graphs show the result of the experiment. The tables will demonstrate the experimental and theoretical deflection for each case. The graphs will show the relationship between the load applied and deflection, in addition to compare the experimental deflection and theoretical deflection.
The strength of a muscle is proportional to the surface area of its cross section.
Laboratory report – First Draft Determine the acceleration due to gravity using a simple pendulum Objective The objective of this practical is to determine acceleration due to gravity ‘g’ using the simple pendulum model. This is shown when a period of oscillation is seen to be independent of the mass of the mass
Below are two tables in which I have recorded the data which I obtained during the experiment. The first table reflects the Relationship between the deflection/flexion of the cantilever and the mass of the load and the second table reflects the relationship between the flexion of the cantilever and the length of the cantilever.