Curriculum Portal

neurologyYou need to know

• A scalar quantity has magnitude only, while a vector quantity has both magnitude and direction.
• Examples of scalar quantities include distance, speed, mass, time, energy, work done, pressure and temperature.
• Examples of vector quantities include displacement, velocity, acceleration, force, weight and momentum.
• A force is a push or pull acting on an object due to an interaction with another object.
• Contact forces include friction, air resistance, tension, compression and normal contact force; non-contact forces include gravitational, electrostatic and magnetic forces.
• Forces can change an object’s speed, direction of motion or shape, depending on the size and direction of the resultant force.
• Weight is the gravitational force acting on an object, it acts vertically downwards, and it is calculated using `W = mg`.
• Work is done when a force causes an object to move through a distance, and work done is calculated using `W = Fs` when the force acts in the direction of movement.
• One joule is the work done when a force of 1 newton moves an object through a distance of 1 metre in the direction of the force.
• When work is done against friction, energy is transferred to the thermal energy stores of the objects and their temperature increases.
• Elastic deformation is when an object returns to its original shape after the force is removed, while inelastic deformation is when it does not return fully to its original shape.
• For a spring that obeys Hooke’s law, extension is directly proportional to force up to the limit of proportionality, so `F = ke`.
• The work done in stretching or compressing a spring is equal to the elastic potential energy stored and is calculated using `E = \frac{1}{2}ke^2`.
• A moment is the turning effect of a force about a pivot, and it is calculated using `M = Fd`, where `d` is the perpendicular distance from the pivot to the line of action of the force.
• The principle of moments states that an object is balanced when the total clockwise moment equals the total anticlockwise moment.
• Pressure is force per unit area and is calculated using `p = \frac{F}{A}`; one pascal is equal to one newton per square metre.
• Pressure in a fluid increases with depth because a taller column of fluid above a point has greater weight, and the pressure difference is calculated using `\Delta p = \rho g \Delta h`.
• Distance is the total length travelled and is a scalar, while displacement is the straight-line distance from start to finish in a stated direction and is a vector.
• Speed is a scalar measure of distance travelled per unit time, while velocity is a vector measure of displacement per unit time.
• Newton’s laws state that objects remain at rest or move at constant velocity unless acted on by a resultant force, acceleration is proportional to resultant force and inversely proportional to mass as `F = ma`, and interacting objects exert equal and opposite forces on each other.

• Classify physical quantities as scalars or vectors by deciding whether direction is needed as well as magnitude.
• Represent vector quantities using scaled arrows, with arrow length showing magnitude and arrow direction showing the direction of the vector.
• Calculate the resultant of multiple vectors by adding vectors in the same direction, subtracting vectors in opposite directions, or using scale diagrams for angled vectors.
• Resolve a force into horizontal and vertical components by drawing a right-angled triangle and using trigonometry to calculate the component sizes.
• Calculate weight, work done, spring extension energy, moments, pressure and fluid pressure difference by selecting the correct equation, substituting values with standard units and giving the correct unit.
• Apply the principle of moments to balanced systems by equating total clockwise and anticlockwise moments around the pivot.
• Interpret distance-time and velocity-time graphs by using gradients for speed or acceleration and areas under velocity-time graphs for displacement.
• Apply the constant acceleration equations of motion to calculate displacement, initial velocity, final velocity, acceleration or time when acceleration is uniform.
• Apply Newton’s laws to explain motion by identifying the resultant force and linking it to acceleration, constant velocity or terminal velocity.
• Solve momentum problems using `p = mv`, change in momentum, force from rate of change of momentum, and conservation of momentum in collisions or explosions.