# Physics AS definitions

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 Author: jpopat ID: 190684 Filename: Physics AS definitions Updated: 2013-04-14 15:57:34 Tags: Physics definitions Folders: Description: Physics AS definitions Show Answers:

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1. Acceleration
Change in velocity divided by time taken
2. Speed
Distance travelled divided by time taken
3. Velocity
Displacement divided by time taken
4. Displacement
The straight line distance from a reference point in a single specified direction
5. Vector
Quantities that have both magintude and direction
6. Scalar
Quantities that are fully defined by by magnitude only
7. Equilibrium
• No resultant force
• No resultant moment
8. Moment
Force multiplied by the perpendicular distance from the line of action of the force to the pivot
9. Principle of moments
Sum of clockwise moments is equal to sum of anti-clockwise moments when the object is in equilibrium about the same pivot
10. Centre of gravity
The single point where the entire weight of a body appears to act
11. Couple
A pair of equal and opposite forces whose lines of action do not coincide
12. Torque of a couple
One of the forces multiplied by the perpendicular distance between the forces
13. Density
Mass divided by volume
14. Pressure
Force divided by area
15. Spring constant
Force divided by extension
16. Hooke's Law
Extension is directly proportional to force provided the elastic limit has not been exceeded
17. Stress
Force divided by cross-sectional area
18. Strain
Extension divided by original length
19. Young's Modulus
Tensile stress divided tensile strain
20. Ductile material
Can be easily and permenantly stretched into thin wires
21. Elastic
Materials return to their original shape and size when the applied force is removed
22. Elastic limit
The maximum load up to which the material can regain its original shape and size when the load is removed
23. Plastic
24. Weight
The force of gravity on the mass of a body
25. Joule
The work done when a force of 1N moves its point of application by 1m in the direction of the force
26. Kinetic energy
The energy of a body due to movement

27. Newton
The force needed to give an acceleration of 1ms-2 to a mass of 1kg
28. Graviational potential energy
The energy a body has due to its position

29. Power
Work done divided by time
30. Work
Force multiplied by distance moved in the direction of the force
31. Braking distance
Distance travelled from when the brakes are applied until the car comes to a stop
32. Thinking distance
• Distance travelled during the drivers reaction time before the brakes are applied
• =speed x reaction time
33. Stopping distance
Thinking distance + braking distance
34. UTS
The maximum stress a material can withstand before fracture
35. Strain energy (3 methods)
• Area under F-x graph
36. Thinking distance
= speed x reaction time