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neurologyYou need to know

• A scalar quantity has magnitude only, whereas a vector quantity has both magnitude and direction.
• Examples of scalar quantities include mass, time, distance, speed, energy and temperature.
• Examples of vector quantities include force, weight, displacement, velocity, acceleration and momentum.
• A force is a push or pull on an object caused by interaction with another object or field.
• Forces can change an object’s speed, direction of motion, or shape.
• Contact forces require physical contact between objects, such as friction, air resistance, tension and normal contact force.
• Non-contact forces act without physical contact, such as gravitational force, electrostatic force and magnetic force.
• Weight is the gravitational force acting on an object, it acts downwards towards the centre of the Earth, and is calculated using `W = mg`.
• Work is done when a force causes an object to move through a distance in the direction of the force.
• Work done is calculated using `W = Fs`, where work done is in joules, force is in newtons and distance is in metres.
• One joule is the work done when a force of 1 newton moves an object 1 metre in the direction of the force.
• When work is done against friction, energy is transferred to the thermal store of the objects and their temperature increases.
• More than one force is needed to stretch, bend or compress an object because deformation requires forces acting in different directions on different parts of the object.
• Elastic deformation happens when an object returns to its original shape after the force is removed; inelastic deformation happens when it does not return to its original shape.
• For a spring within its limit of proportionality, extension is directly proportional to force and follows Hooke’s law, `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`.
• Distance is the total length travelled and is a scalar, whereas displacement is the straight-line distance from start to finish in a stated direction and is a vector.
• Speed is the rate of change of distance and is a scalar, whereas velocity is the rate of change of displacement and is a vector.
• Typical speeds are about 1.5 m/s for walking, 3 m/s for running, 6 m/s for cycling, 13 m/s for urban car travel, 25 m/s for motorway car travel and 330 m/s for sound in air.
• Newton’s laws state that objects remain at rest or at constant velocity unless acted on by a resultant force, acceleration is proportional to resultant force and inversely proportional to mass, and every force has an equal and opposite force of the same type on another object.

• Represent vector quantities using arrows where the arrow length shows magnitude and the arrow direction shows direction.
• Calculate the resultant of multiple vectors by adding vectors in the same direction and subtracting vectors in opposite directions, or by using a scale vector diagram for angled vectors.
• Calculate weight using `W = mg`, selecting the correct gravitational field strength and giving the answer in newtons.
• Calculate work done using `W = Fs`, using the distance moved in the direction of the force.
• Calculate speed or average speed using `v = \frac{s}{t}`, including for non-uniform motion by using total distance divided by total time.
• Interpret distance-time graphs by using the gradient to find speed and recognising horizontal sections as stationary periods.
• Interpret velocity-time graphs by using the gradient to find acceleration and the area under the graph to find displacement.
• Apply the SUVAT equations to uniformly accelerated motion by selecting known quantities, choosing a suitable equation and solving with correct units.
• Calculate resultant force, mass or acceleration using `F = ma`, and use the result to predict changes in motion.
• Explain terminal velocity by comparing weight and drag, identifying when the resultant force becomes zero and acceleration stops.