2684129
Descrição
FlashCards por Michael Priest, atualizado more than 1 year ago
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Criado por Michael Priest
mais de 9 anos atrás
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| Questão | Responda |
| Define: scalar and vector quantities | Scalar: magnitude only Vector: magnitude and direction |
| Give an example of a scalar and a vector quantity | Scalar: distance, speed, mass Vector: displacement, velocity, weight |
| Define: displacement | Straight line distance between two points |
| Define: speed | Rate of change of distance |
| Define: velocity | Rate of change of distance |
| Define: acceleration | Rate of change of velocity |
| Define: equilibrium | Resultant moment = zero Resultant force = zero |
| Define: moment | Product of force and perpendicular distance to the pivot |
| Define: principle of moments | In equilibrium, total anticlockwise moments = total clockwise moments about a point |
| Define: couple | Two equal and opposite forces acting along parallel lines of action Couple = force x shortest distance between their lines of action |
| Define: centre of mass | The point where all the mass of an object can be considered to act |
| Define: centre of gravity | The point where all the weight of an object can considered to act |
| What does the gradient of a displacement-time graph represent? | speed |
| What does the gradient of a velocity-time graph represent? | acceleration |
| What does the area under a velocity-time graph represent? | displacement |
| Why can horizontal motion and vertical motion be treated independently? | They act at 90 degrees to each other or Horizontal motion is constant and vertical motion involves acceleration |
| State Newton's 1st law | Objects remain at rest or constant velocity unless external forces act |
| State Newton's 2nd Law | Acceleration is proportional to resultant force (F = ma) |
| State Newton's 3rd Law | For every action there is an equal and opposite reaction |
| Describe one situation where Newton's 1st law applies | Constant velocity so no friction or air resistance would occur in space or another situation where friction is negligible e.g. linear air track |
| Describe how the forces acting on a falling object change as it falls | Initially, weight is greater than air resistance. As speed increases, air resistance increases, until air resistance = weight, so no resultant force and no acceleration |
| What is meant by conservation of energy? | Energy is neither created nor destroyed only changed from one form to another |
| Define: density | The ratio of an objects mass to its volume |
| Define: tensile stress | The force per unit area of cross-section |
| Define: tensile strain | Extension per unit length |
| State Hooke's Law | Extension of a material (or spring) is directly proportional to the applied force, up to the limit of proportionality |
| What is meant by 'elastic limit'? | The point beyond which the material will not return to its original size and shape |
| Define: Young Modulus | The ratio of tensile stress to tensile strain |
| What does the area under a stress vs. strain graph represent? | Energy stored per unit volume |
| What does the area under a force vs. extension graph represent? | Energy stored |
| What does the gradient of a stress vs. strain graph represent? | Young Modulus |
| Which equation starts the derivation for the energy stored in a stretched material? | Work = Force x displacement |
| Define: Breaking Stress | The breaking force per unit area of a material |
| Define: progressive wave | The movement of a disturbance from a source, which transfers energy and momentum from the source to places around it |
| Define: stationary wave | Stationary or standing waves result from the superposition of two progressive waves with same frequency and amplitude |
| Define: Transverse wave | Particles in the path of the wave oscillate at 90 degrees to the direction of wave propagation |
| Define: Longitudinal wave | Particles in the path of the wave oscillate parallel to the direction of wave propagation |
| What is the phase difference between particles one wavelength apart on a progressive wave? | 0, they are in phase |
| What is the phase difference between particles half a wavelength apart on a stationary wave? | antiphase / 180 degrees |
| What is the phase difference between particles half a wavelength apart on a progressive wave? | 180 degrees / antiphase |
| What property of light waves does polarisation demonstrate? | They are transverse |
| If light refracts towards the normal what does this mean for the refractive indices of two materials? | Refractive index of material 1 is lower than material 2 |
| If light refracts away from the normal what does this mean for the refractive indices of two materials? | Refractive index of material 1 is higher than material 2 |
| State Snell's Law of Refraction | When a ray of monochromatic light travels from a less dense material to a more dense material it will bend towards the normal (provided it approaches the boundary at an angle other than 90 degrees) |
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