- Created by: AStarStudent2004
- Created on: 19-05-19 19:35
SP1a Vectors and Scalars
- All forces have both a magnitude (size) and a direction, and are measured in newtons (N).
- Vector quantities - quantites that have size and direction. Forces are vectors.
- Scalar quantites - quantities that only have size, examples include distance, speed, energy and time.
- Displacement is the distance covered in a straight line.
- The speed - how far an object moves in a certain time.
- Velocity - speed in a particular direction.
- Acceleration - a measure of how fast velocity is changing.
- Momentum - a combination of mass and velocity.
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SP1b Distance/Time Graphs
- Speed (m/s) = distance (m) ÷ time (s)
- Calculated usng light gates - more accurate.
- Adverage speeds for: walking - 1.4m/s, cycling - 6 m/s and train - 55m/s.
- WInd - 5-20m/s and sound in air - 340m/s
- Horizontal lines: object stationary
- Straight lines: constant speed
- Steep lines: faster constant speed
- Curves: acceleration
- Gradient: the speed of the object
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- Acceleration - change in velocity , units are m/s ² and is a vector quantity.
- accleration (m/s²)= change in velocity (m/s) ÷ time (s)
- a = (v - u) ÷ t (v - final velocity, u - intial veloctiy)
- (final velocity)² - (initial velocity)² = 2 x acceleration x distance
- v²-u²= 2ax
- If there are no forces acting on a object in free fall, the acceleration due to gravity is 9.8m/s² or 10m/s².
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SP1d Velocity/Time Graphs
On a velocity/time graph:
- horizontal lines: constant velocity
- sloping lines: accelerating (steeper the line, greater the acceleration)
- line below horizontal axis: negative velocity (object moves opposite direction)
- area under a velocity/time graph: distance travelled (distance= velocity x time/ base x height)
- if the object is accelerating (sloping line), split the shape into a triange (area = 0.5 x b x h) and rectangle and find their areas separately.
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