Unit 1 - Motion, forces and energy Flashcards
Common units of length
mm, cm, m, km
Common units of time
ms, s, min, h, d
Common units of volume
cm^3, m^3
Period
The time taken for a full oscillation (start - start)
Vectors
Measurements that have specific direction and magnitude
Scalars
Measurements that have magnitude but no specific direction in which they act
Scalar examples
- Time
- Speed
- Pressure
- Distance
- Mass
- Energy
Vector examples
- Velocity
- Displacement
- Momentum
- Weight
- Acceleration
- Force
Average speed calculation
Average speed(m/s) = Total distance travelled(m) ÷ Total time taken(s)
Velocity
The speed of an object in a specific direction
Acceleration
The change in velocity per unit time
Deceleration/negative acceleration
The negative change in velocity per unit time
Acceleration calculation
Acceleration(m/s^2) = Change in velocity (m/s) ÷ time taken (s)
Notation for deceleration
- Negative acceleration e.g. -2m/s^2
Speed
The change in distance travelled per unit time
Displacement
How far an object is from its starting position in a particular direction
Features of a distance-time graph
- Straight sloping line = constant speed
- Straight loping line of higher gradient = faster constant speed
- Flat/horizontal line = stationary
- Gradient = Speed
Features of a speed-time graph
- Flat horizontal line at zero speed = stationary
- Flat horizontal line above zero speed = constant speed
- Upward sloping line = acceleration - steeper gradient = higher acceleration
- Downward sloping line = deceleration
- Gradient = acceleration
Figure for acceleration of gravity/acceleration of free fall
g = 9.8m/s^2
Calculating distance travelled on a speed-time graph
Calculate the area under the line
Relationship with air resistance and acceleration
- More air resistance = less acceleration
- More acceleration = more air resistance
Terminal velocity
The ‘top speed’ of any object when falling
When terminal velocity occurs
When the downward force of weight is balanced by air resistance
Weight
A gravitational force on an object that has mass