Topic 3: Biomechanics

What areas of biomechanics have you already covered on the course?

Levers Name the 3 different types of lever. What are the 3 components of each lever and how do these differ in each lever? How can levers provide us with a mechanical advantage? Levers in sport

Newton’s Laws in Sporting Situations Can you name and give the definition for each of Newton’s Laws? How can they be applied to a sporting situation (e.g. a penalty flick in hockey)? Newton’s Laws in Sporting Situations

Stability and Centre of Mass Centre of mass – the point about which all mass of a body is concentrated Stability is concerned with remaining balanced by keeping your centre of mass over your base of support. How do we increase our stability? Ensure centre of mass is in centre of base of support Lower our centre of mass closer to the ground Increase our mass Stability and Centre of Mass

Stability exam question Stability can be a key factor determining success or failure in many sports. Define the term stability and outline 3 factors that would determine the stability of a performer. (4 marks) Describe one sporting situation where stability would be an advantage and one where instability would be an advantage. (2 marks)

New topics Exercise physiology and applied movement analysis Linear motion Angular motion Projectile motion Fluid mechanics

Calculate the ‘moment of force’ at the knee in both exercises Calculate the ‘moment of force’ at the knee in both exercises. You must show your working. (i) Front squat (2) (ii) Smith machine squat (2)

Calculating forces (converting mass into Newtons) Force equals mass x acceleration (F=ma is Newton’s 2nd Law) The force exerted by a mass of 1kg is 9.81N (because this is the acceleration force due to the effects of gravity) You should have a calculator with you in the exam but 10N is also accepted as a conversion. In this question 100kg equals 981N. A ‘moment’ is a turning force. Multiplying 981 by 0.30m and 0.40m will give us our answer in Nm (Newton metres). You must always remember the units or you will definitely drop marks

Linear motion a) Explain the the difference between a scalar and a vector using examples. (4 marks) b) What units are used to measure speed and velocity? c) What is acceleration and how is it calculated? What units are used? (3 marks)

Exam Questions Calculate the distance of 40 lengths of a 25m swimming pool. 1000m (1km) Calculate the displacement of a 1km race in a 50m swimming pool. 0m (as the start and end are at the same place) Dafne Schippers broke the 200m record with a time of 21.63s. Calculate her average speed. 200m/21.63s = 9.25m/s

Exam Questions Usain Bolt broke the 100m record with a time of 9.58s. Calculate his average velocity. 100m/9.58s = 10.44m/s During this race Usain completed the first 20m in 2.89s. His velocity at 20m was 6.92m/s. Calculate the acceleration between 0-20m. (6.92m/s – 0m/s) / 2.89s = 2.39m/s/s As a cyclist crosses the line they sit up and raise their hands in victory immediately slowing themselves. When they crossed the line they were moving at 9m/s but two seconds later this was 5m/s. Calculate the deceleration. (5m/s – 9m/s) / 2s = minus 2m/s/s

Distance-Time Graphs and Velocity-Time Graphs On these graphs the time is always along the horizontal axis and the distance or velocity will be on the vertical axis. For these 2 types of graph you would need to know what these each represent: A line going diagonally up at 45 degrees. A line going up at a steeper angle. A line going horizontally. A line going diagonally downwards.

Explanation A line going diagonally up at 45 degrees. On distance time graph this shows a constant speed. On velocity time graph it shows constant acceleration. A line going up at a steeper angle. On distance time graph this shows a greater speed. On velocity time graph it shows greater rate of acceleration. A line going horizontally. On distance time graph this shows that movement has stopped. On velocity time graph it shows constant velocity. A line going diagonally downwards. On distance time graph this shows that the object/person is moving back to the start position. On velocity time graph it shows constant deceleration.

You may be asked to interpret a graph or even draw a graph based on data you are given What is the speed at points a,b,c and d?

What is the velocity and acceleration at points a,b and c?

Draw a velocity time graph showing a sprinter: Reaching 9m/s in the first 3 seconds. Then maintaining this speed for 3 seconds. Decelerating by 1m/s/s for the next 3 seconds.