-A body continues in a state of rest or uniform velocity unless acted upon by an external or unbalanced force
-Taking a penalty
Newtons 2nd law:
-A body's rate of change in momentum is proportional to the size of the force applied and acts in the same direction as the force applied
-Hitting the bottom of a snooker ball to achieve backspin
Newtons 3rd law:
-For every action force applied to a body there is an equal and opposite reaction force
-A ball hitting the post,the post will produce an equal and opposite reaction
Internal force is generated by the contraction of skeletal muscles
External force is generated from outside the body and acts upon it
Balanced net force has no change in motion
Unbalancednet force has a change in motion
Vertical forces:
Weight
Reaction forces
Horizontal forces:
Friction
Air resistance
Weight is the gravitational pull that the earth exerts on a body and is measured in newtons
Weight= mass x acceleration
Reaction forces are equal and opposite forces exerted by a body in respone to the action force placed upon it
Friction is the force opposing motion of two surfaces in contact
Air resistance is the force opposing motion travelling through the air
Magnitude is the size and direction of the force
CoM is the point at which a body is balanced in all directions,the point form which appears to act
Stability is the ability of the body to resist motion and remain at rest,or for a body to withstand a force applied and return to its original position without damage
Factors affecting stability:
Mass of body-greater mass,greater stability
Height of CoM-lower CoM,greater stability
Base of support-greater size of BoS,greater stability
Line of gravity-more central LoG,greater stability
Limb kinematics:
-Study of movement in relation to time and space
-Evaluation of bio mechanical measurements
-Computer software and video cameras
-Cricketer finding acceleration at the shoulder joint