# G481 Key Definitions

This is a set of flashcards for the key definitions from unit G481: Mechanics from OCR A physics

HideShow resource information
• Created by: abbiemca
• Created on: 20-04-16 23:59
Speed
Rate of change of distance (m/s)
1 of 37
Average Speed
Total distance travelled/time taken (m/s)
2 of 37
Displacement
Distance moved in a stated direction (m)
3 of 37
Velocity
Rate of change of displacement (m/s)
4 of 37
Scalar Quantity
A quantity with magnitude (size) but not direction
5 of 37
Vector Quantity
A quantity with magnitude (size) and direction
6 of 37
Acceleration
Rate of change of velocity (m/s^2)
7 of 37
Thinking Distance
Distance traveled from when the driver sees a problem and the brakes are applied
8 of 37
Braking Distance
Distance travelled from when the driver starts braking to when the car stops
9 of 37
Stopping Distance
Distance travelled from when the driver sees a problem to when the car stops (thinking distance + braking distance)
10 of 37
Density
Mass per unit volume (kg/m^3)
11 of 37
Newton
One Newton is the force that causes a mass of one kilogram to have an acceleration of one metre per second squared (N)
12 of 37
Weight
The weight of an object is the gravitational force acting on the object (N)
13 of 37
Centre of Gravity
A point where the entire weight of an object appears to acct
14 of 37
Drag
The resistive force experienced by an object moving through a fluid
15 of 37
Terminal Velocity
At terminal velocity drag = weight
16 of 37
Equilibrium
At equilibrium net resultant force = 0 and net moment = 0
17 of 37
Moment of a Force
The force multiplied by the perpendicular distance from a specified point (Nm)
18 of 37
Principle of Moments
If an object is balanced, then the sum of the clockwise moments about a pivot is equal to the sum of the anticlockwise moments about the same pivot
19 of 37
Couple
A couple is a pair of equal and opposite forces, which tends to produce rotation only
20 of 37
Torque of a Couple
The force multiplied by the perpendicular distance between the forces (Nm)
21 of 37
Pressure
Force per unit area (Pa)
22 of 37
Work Done
The force multiplied by distance moved in the direction of the force (J)
23 of 37
Joule
The work done by a force of one newton acting over a distance of one metre
24 of 37
Potential Energy
The stored energy associated with a force due to the position of a body (J)
25 of 37
Gravitational Potential Energy
The stored energy associated with the weight of a body at a given vertical height (J)
26 of 37
Kinetic Energy
The energy of a body due to the motion of the body (J)
27 of 37
Conservation fo Energy
Energy cannot be created or destroyed, it can only be transformed into other forms
28 of 37
Power
Rate of work done with respect to time (W)
29 of 37
Hooke's Law
Extension of material is proportional to force applied to material
30 of 37
Watt
One joule per second
31 of 37
Tensile Stress
The force per unit cross-sectional area of a material
32 of 37
Tensile Strain
The extension per unit length of a material
33 of 37
Young's Modulus
Tensile stress per unit tensile strain
34 of 37
Ultimate Tensile Stress
The maximum stress a material can stand
35 of 37
Elastic Deformation
Material regains its original shape when stress is removed
36 of 37
Plastic Deformation
Material is permanently distorted when dress is removed
37 of 37

## Other cards in this set

### Card 2

#### Front

Total distance travelled/time taken (m/s)

Average Speed

### Card 3

#### Front

Distance moved in a stated direction (m)

### Card 4

#### Front

Rate of change of displacement (m/s)

### Card 5

#### Front

A quantity with magnitude (size) but not direction