Biomechanics • Mechanics of movement: – vectors and scalars – velocity, acceleration and momentum/impulse in sprinting – Newton’s Laws applied to movements – application of forces in sporting activities – projectile motion – factors affecting distance, vector components of parabolic flight – angular motion – conservation of angular momentum during flight, moment of inertia and its relationship with angular velocity. – vectors and scalars – velocity, acceleration and momentum/impulse in sprinting

Recap: Inertia Inertia is the reluctance of a body to move or change its state of motion Objects will stay in their state of inertia (i.e. stationary or moving at a constant velocity) unless a force overcomes that inertia. The inertia of a body is directly proportional to its mass Therefore an object with a greater mass requires a larger force to overcome its inertia and change its state of motion.

Recap: Momentum Momentum is the amount of motion a body has Momentum is calculated as: Mo = Mass (kg) x Velocity (ms-1) The more massive, or the faster an object, the more momentum it has. Momentum is linked to inertia – the more momentum something has, the harder it is to stop!

What is each of their momemtum when running at 4ms-1 Ben Morgan 1m 93 117 kg Richie Gray 2m 08cm 120 kg Leigh Halfpenny 1m 78cm 83 kg What is each of their momemtum when running at 4ms-1

Impact Momentum becomes more important in sporting situations where collisions or impacts occur. The outcome of a collision depends largely on the momentum of each of the colliding bodies.

Impulse = Ft = Change in momentum The change in momentum during a collision depends on the ‘impulse’ of an impact The impulse is the force that is applied multiplied by the time its applied for Impulse = F x t or Ft The force applied and the time it is applied for determines the change in momentum of an object. Therefore… Impulse = Ft = Change in momentum

Impulse So… this means that an increase in the force applied, or an increase in the time its applied will result in a GREATER change in momentum Equally… … for the same change in momentum, if it occurs over a longer period of time, the force required will be less. Change in Momentum = F x T

Examples of using impulse to change momentum in sport: Cricket Hockey:

Examples of using impulse to change momentum in sport: Shot put: Gymnastics

What’s being shown in this diagram?

Which impulse would make the athlete accelerate? Impulses can be shown as force – time graphs Both these impulses are made as a result of an athlete landing and then pushing off from one foot during a sprint. Which impulse would make the athlete accelerate? Force (N) If the force is positive, it causes the athlete to accelerate Time (s) If the force is negative, it causes the athlete to decelerate The longer the force is applied for, the bigger the impulse (change in momentum) The area under (or over) the line is equivalent to F x t = the impulse

Impulse Area 2 – Represents the impulse of a body due to the ground reaction force – it’s a positive impulse Area 1 – represents the impulse of a body landing on the ground – it’s a negative impulse

Impulse Small –ve and large +ve impulse – shows a body that is accelerating e.g. High jumper Large –ve and small +ve impulse – shows a body that is decelerating e.g. volleyball player landing +ve and –ve are equal – shows a runner travelling at a constant speed

Exam Qu The following force–time graphs were obtained during the various stages of a runner’s 100-metre sprint. Using Figure 6, identify which graph is associated with each of the following phases of a 100-metre sprint, giving reasons for your answers: (i) early in the sprint; (ii) during the middle part of the sprint; and (iii) towards the end of the sprint. (6 marks)

X = a foot contact in the middle of a sprint Y = a point where the athlete is just pushing on the ground at the start of a sprint Z = a foot contact just after the player has begun sprinting

Equation You Say We Pay Speed

Equation You Say We Pay Acceleration

Equation You Say We Pay Impulse

Equation You Say We Pay Weight

Equation You Say We Pay Momentum

Equation You Say We Pay Velocity

Equation You Say We Pay Change in Momentum