P1B - Motion Flashcards
Formula for speed
Distance/time, usually in m/s
What is the difference between speed and velocity?
Velocity is speed of an object in a specific direction.
E.g. if a swimmer swims 50m there and back in 20 seconds, their speed is 5m/s but their velocity is 0 because they ended up in the same position.
What is the difference between distance and displacement?
Distance is the total length of the path taken by an object while displacement is the difference in distance between an object’s starting point and ending point
What is acceleration, unit and formula
Acceleration is the rate of change of velocity.
Change in velocity/time taken.
M/s²
What is the difference between scalar and vector qualities?
Scalar - measurements that have only magnitude
Vector - measurements that have both magnitude and direction
Interpret different lines on a distance time graph
Straight, sloping line - constant speed
Straight, sloping line of higher gradient - faster constant speed
Flat line - stationary
Distance-time graph gradient
Change in y (distance)/change in x(time)
Interpret different lines on a speed-time graph
Flat line at 0m/2 - stationary
Flat line above 0m/s - constant speed
Upward sloping line - accelerating. Steeper gradient = higher acceleration
Downward sloping line - deceleration
How to find distance on speed-time graph?
Calculate the area under the line
How to find acceleration on speed-time graph?
The gradient of the line
How does a speed-time graph show whether acceleration is constant or not?
Straight line - constant acceleration
Curved line - changing acceleration
What is the acceleration of gravity?
The acceleration of a falling object caused by gravity.
All objects accelerate towards Earth at the same, constant acceleration as long as air resistance is not a factor.
What 3 factors affect air resistance?
- Cross sectional area - larger area, more air particles to push against
- Air density
- Speed - the faster the more particles an object hits per second
How does the acceleration of an object vary during its fall?
As the object begins to fall, it rapidly accelerates at 9.8m/s^2 due to the gravitational force of Earth. As its speed increases, so does the air resistance because the faster the object moves, the more air molecules it hits/second. After some time, terminal velocity is reached (constant velocity) when the weight and air resistance become balanced.
Why velocity-time graphs for falling objects are often curved.
Mass is… to acceleration
inversely proportional
How to calculate average speed in problem: speed changes from xm/s to ym/s in x seconds
xm/s+ym/s divided
The acceleration of free fall near the Earth’s surface is 9.8m/s^2. This can be rewritten as..
This can also be written as a gravitational
field strength of 9.8newtons/kg
