newtons laws of motion, force and the use of technology

whats newtons 1st law of motion

• ‘ a body continues in a state of rest or uniform velocity unless acted upon by an external or unbalanced force

• law of inertia, inertia is the resistance of a body to change its state of motion

• A golf ball will remain still unless acted on by the golf club

what is newtons 2nd law of motion

• ‘ a body’s rate of change of movement is proportional to the size of the force applied and acts in the same direction as the force applied’

• law of acceleration, as acceleration is proportional to the size of force applied

• when the velocity of the golf ball been hit is proportional to the amount of force used to on it

what is newtons 3rd law of motion

‘ for every action force applied to a body there is an equal and opposite reaction’

• law of reaction and states

• When you jump, your feet apply force to the ground, and the earth applies an equal and opposite reaction force that pushes you into the air

what is velocity

the rate of change of displacement

Velocity(s)= displacement/ time taken

what is momentum

the quantity of motion possessed by a moving body

momentum= mass x velocity

what is acceleration

Acceleration= (final velocity - initial velocity) / time taken

measured in M/S

What is force

force is a push or pull which alters the state of motion of a body

Force= mass x acceleration

F=MA

Measured in newtons N

Types of force

• internal force

  • contraction of skeletal muscles

• external force

  • from outside the body

  • weight, reaction, friction and air resistance

what are the five effects force can have

• can create a motion

• can accelerate a body

• can decelerate a body

• can change direction of a body

• can change the shape of a body

what is net force

• the sum of all forces acting on a body( resultant force)

• if net force is 0 then there is no change in motion

describe the vertical forces

• weight

  • the gravitational pull that the earth exerts on a body

  • weight= mass x acceleration due to gravity

  • 10 m/s

• Reaction

  • is the equal and opposite force exerted by a body

  • measured in Newtons

what are the horizontal forces

Friction

• the force that opposes the motion of two surfaces in contact

• Measured in newtons

Air resistance

• force that opposes motion of body travelling through the air

• measured in newtons

what are the factors that can affect friction

• roughness of the ground surface

• roughness of the contact surface

• temperature, if higher temp friction is higher

• size of normal reaction

what are the factors affecting air resistance

• velocity

• shape( streamlining)

• frontal cross sectional area

• smoothness of surface body( lycra suits for cyclists)

whats a free body diagram

• a clearly labelled sketch showing all of the forces acting on a body at one particular time

what is limb kinematics

• the study of movement in relation to time and space, allowing limb displacement, velocity and acceleration to be assessed

what are force plates

used to measure the size and direction of ground reaction forces on the athlete and can be used to asses acceleration, work and power output

what are wind tunnels

used to measure air resistance and aim to improve the flow of air around an object streamlining its path through the oncoming air

what is the centre of mass

• the point in which the body is balanced in all directions

• the centre of mass can also move outside the body and act as a point of rotation

whats the Fosbury flop technique

in high jump to move the centre of mass outside the body and below the bar

what is stability

• the body’s ability to resist motion and remain at rest

• also to withstand a force applied and return to its original postion

what are the factors affecting stability

• mass of the body( more mass better stability)

• height of the centre of mass( lower is better)

• Base and support

• line of gravity

what are the components of lever systems

• lever(bone)

• fulcrum(joint)

• effort(muscular force)

• load(weight or resistance)

what is the 1st class lever

• E-F-L

• L-F-E

• fulcrum is in the middle

• extension of neck when preparing to header a football

what is the 2nd class lever

• E-L-F

• F-L-E

• load is in the middle

• ball of the foot at the take off phase of a high jump

what is the 3rd class lever

• L-E-F

• F-E-L

• effort is in the middle

  flexion at the elbow in. bicep curl

describe the efficiency of the lever system

the order and distance of the lever components from the fulcrum is important for their function

• the distance from the fulcrum to the effort is known as ‘effort arm’

• the distance from the load to the fulcrum is know as the ‘load arm’

• the greater the distance of the effort or load to the fulcrum the more significant the effort or load becomes

describe the efficiency of the lever system (2)

• longer levers can generate more force as the load arm becomes longer therefore greater acceleration to projectiles

• the length of the effort and load arm gives a lever system a mechanical advantage or a mechanical disadvantage

• second class lever has the mechanical advantage to move a large load with small effort

• the third class lever has the mechanical disadvantage requiring a large effort to move a relatively small load, however can generate lots of acceleration over a large range of movement