Curriculum Portal

neurologyYou need to know

• Linear motion is movement along a straight or curved path in which all parts of a body travel the same distance in the same direction at the same time.
• An unbalanced direct force whose line of action passes through the centre of mass produces linear acceleration without a turning effect, such as a sprinter accelerating forwards or a barbell moving vertically.
• Distance is the total path travelled and is a scalar measured in metres, whereas displacement is the straight-line change from start to finish and is a vector measured in metres with a stated direction.
• Speed is the rate of change of distance and is calculated using `speed = distance/time`, whereas velocity is the rate of change of displacement and includes direction; both are measured in `m s^{-1}`.
• Acceleration is the rate of change of velocity, calculated using `a = (v-u)/t` and measured in `m s^{-2}`, while deceleration is acceleration acting opposite to the direction of motion.
• On a distance–time graph, the gradient represents speed, a steeper gradient represents greater speed, a straight sloping line represents constant speed, and a horizontal line represents no movement.
• On a speed–time graph, the gradient represents acceleration and the area under the line represents distance, while on a velocity–time graph the gradient represents acceleration and the signed area represents displacement.
• Angular motion is rotation about an axis and is changed by torque, which is produced when an eccentric force acts away from the axis of rotation and is calculated using `τ = Fd_⊥` in newton metres.
• The longitudinal axis runs from head to toe and is used in a pirouette, the transverse axis runs from side to side and is used in a somersault, and the frontal axis runs from front to back and is used in a cartwheel.
• One radian is the angle formed when the arc length equals the radius, and angular velocity is the rate of angular displacement calculated using `ω = θ/t` and measured in `rad s^{-1}`.
• Moment of inertia is a body's resistance to angular acceleration about a specified axis and can be modelled as `I = Σmr^2`, with units of `kg m^2`.
• Moment of inertia increases when mass increases or when more mass is distributed farther from the axis of rotation, and it decreases when mass is moved closer to the axis.
• Angular momentum is the quantity of angular motion, calculated using `L = Iω` and measured in `kg m^2 s^{-1}`.
• The conservation of angular momentum states that angular momentum remains constant when no net external torque acts, so reducing moment of inertia increases angular velocity and increasing moment of inertia decreases angular velocity.
• The angular analogue of Newton's first law states that a rotating body maintains constant angular momentum unless acted upon by a net external torque.
• Air resistance and water drag act opposite to relative motion and are described by `F_D = 1/2 ρC_DAv^2`, so they generally increase with fluid density, speed, frontal cross-sectional area and drag coefficient.
• Streamlining reduces the drag coefficient by allowing smoother fluid flow, while shape and surface characteristics affect boundary-layer separation; mass does not directly alter drag at the same speed and shape but changes the acceleration caused by drag.
• A projectile in flight is acted on by weight downwards and may experience drag opposite its motion and lift perpendicular to the airflow; gravity alone creates a parabolic path, while substantial aerodynamic forces create a non-parabolic path.
• A projectile's horizontal distance depends on release speed, release angle, release height, gravity, drag, lift and spin, with release speed usually having the greatest effect.
• Bernoulli's principle links faster airflow with lower static pressure, so an aerofoil and its angle of attack can create a pressure difference that produces lift, while an inverted aerofoil can produce downward lift or downforce; spin creates a Magnus force perpendicular to the flight direction and spin axis, producing deviations such as a hook or slice.

• Calculate distance, displacement, speed, velocity, acceleration and deceleration using the correct equation, SI unit and direction where the quantity is a vector.
• Plot distance–time, speed–time and velocity–time graphs using correctly labelled axes, suitable scales, accurate points and appropriate lines.
• Interpret linear-motion graphs by calculating gradients and areas and linking them to speed, acceleration, distance or displacement.
• Distinguish direct and eccentric forces by identifying whether the line of action passes through the centre of mass or acts at a perpendicular distance from an axis.
• Calculate torque, moment of inertia, angular velocity and angular momentum using appropriate values and SI units.
• Apply conservation of angular momentum to predict and calculate how changing body shape or mass distribution alters angular velocity during flight.
• Interpret graphs of moment of inertia, angular velocity and angular momentum, recognising that `Iω` remains constant when no external torque acts.
• Draw a free-body diagram for a projectile using labelled arrows that show the direction and relative size of weight, drag and any lift force.
• Resolve a force into horizontal and vertical components using a scaled parallelogram of forces or trigonometry.
• Analyse sporting flight paths by relating release conditions, aerodynamic drag, aerofoil design, angle of attack and spin to range, lift, downforce and Magnus-force deviation.