Motion, Energy & Charge

PH1.1 BASIC PHYSICS

Content

• Units and dimensions
• Scalar and vector quantities
• Force
• Free body diagrams
• Movements and stability
• Equilibrium

AMPLIFICATION OF CONTENT Candidates should be able to:

(a) recall and use SI units,

(b) check equations for homogeneity using units,

(c) contrast scalar and vector quantities and give examples of each – displacement, velocity, acceleration, force, speed, time, density, pressure etc.,

(d) appreciate the concept of force and understand Newton's 3rd law of motion,

(e) use free body diagrams to represent forces on a particle or body,

(f) recall and use the relationship ΣF = ma in situations where mass is constant,

(g) add and subtract coplanar vectors, and perform mathematical calculations limited to two perpendicular vectors,

(h) resolve a vector into two perpendicular components,

(i) understand the concept of density, use the equation ρ=m/V to calculate mass, density and volume;

(j) understand and define the turning effect of a force;

(k) recall and use the principle of moments;

(l) understand and use centre of gravity, for example in simple problems including toppling and stability. Identify its position in a cylinder, sphere and cuboid (beam) of uniform density;

(m) understand that a body is an equilibrium when the resultant force is zero and the net moment is zero, and be able to perform simple calculations.

PH1.2 KINEMATICS

Content

• Rectilinear motion.

AMPLIFICATION OF CONTENT Candidates should be able to:

(a) define displacement, mean and instantaneous values of speed, velocity and acceleration,

(b) use graphical methods to represent displacement, speed, velocity and acceleration,

(c) understand and use the properties of displacement-time graphs, velocity-time graphs, acceleration-time graphs, and interpret speed and displacement-time graphs for non-uniform acceleration,

(d) derive and use equations which represent uniformly accelerated motion in a straight line,

(e) describe the motion of bodies falling in a gravitational field with and without air resistance − terminal velocity,

(f) recognise and understand the independence of vertical and horizontal motion of a body moving freely under gravity,

(g) describe and explain motion due to a uniform velocity in one direction and uniform acceleration in a perpendicular direction, and perform simple calculations.

PH1.3 ENERGY CONCEPTS

Content

• Work, Power and Energy.

AMPLIFICATION OF CONTENT Candidates should be able to:

(a) recall the definition of work as the product of a force and distance moved in the direction of the force when the force is constant; calculation of work done, for constant forces, when force is not along the line of motion ( W.D. = Fxcosθ )

(b) understand that the work done by a varying force is the area under the Force-distance graph,

(c) recall and use Hooke's law F = kx, and apply this to (b) above to show that elastic potential energy is 1/2 Fx or 1/2 kx^2,<math>1/2</math>

(d) understand and apply the work – energy relationship Fs mv2 mu2 2 1 2 = 1 − and recall that Ek = 2 1 mv2 ,

(e) recall and apply the principle of conservation of energy including use of gravitational potential energy mgΔh , elastic potential energy 2 1 kx2, and kinetic energy 2 1 mv2,

(f) define power as the rate of energy transfer,

(g) appreciate that dissipative forces e.g. friction, viscosity, cause energy to be transferred from a system and reduce the overall efficiency of the system,

(h) recall and use Efficiency = 100%, Energy input Useful energy obtained ×