Forces And Motion Flashcards
What is distance?
How far an object moves. Doesn’t involve direction and is a scalar quantity.
What is displacement?
Included both distance object moves - measured in a straight line from start to finish point, and the direction of the straight line. Vector quantity.
Measure of how far something is from its staring position.
Speed
Doesn’t involve direction is a scalar quantity. Distance travels every second.
What is the equation for average speed?
Average speed = total distance/time taken
Is the speed of a moving object constant?
Rarely - constantly changing.
Typical values
Walking - 1.5m/s
Running - 3m/s
Cycling - 6m/s
Car - 10 - 30
Aeroplane - 200 - 250
Sound - 330 - 340
Non uniform motion
Motion that’s changing - speed, direction or both
What does the typical speeds depend on
People - age, distance, terrain, fitness
Transport - shape, design, cost, purpose
What equipment can you use when measuring speed
Light gate - measure time
Meter ruler - distance
What is velocity
Speed of object in a dive direction. Vector.
Calculation for non uniform motion
Average speed = total distance/time taken.
Why does motion in circle - Constant speed but changing velocity?
Velocity = vector - speed in a given direction When object in circular path - velocity is always changing.
Speed may be constant - traveling the same distance every second.
However direction is always changing as object moves in circular motion.
What does a distance time graph represent
The distance travelled by an object along a straight line. The speed can be calculated from the gradient.
How can you determine speed at particular time of object accelerating on distance time graph?
Drawing a tangent and measuring the gradient at that time.
Distance time graphs
Straight diagonal like = constant speed
Steeper line = faster speed
Straight horizontal line = stationary
Decreasing slope = decreasing speed.
How can u measure speed of an object in D-T graph
Calculating the gradient of the line.
Equation for acceleration
Change in velocity/time taken
Accelerating = m/s squared
What is an abject slowing down?
Decelerating - negative
What is the acceleration of an object?
A measure of how quickly its velocity changes
Typical accelerations - m/s squared
Family Car - 2-3
Falling object - 10
Rocket - 30
Formula 1 car - 50
Fighter jet - 90-120
What do velocity time graphs represent?
How the velocity of a moving object varies with time
It shows if object moving with constant acceleration and also shows magnitude of acceleration
What do different lines on velocity time graphs represent?
Straight diagonal line - acceleration - steepness - magnitude. Eg steeper = larger acceleration
Flat line = constant velocity - acceleration- 0
How do you work out the acceleration from a velocity time graphs?
From the gradients of the time graph.
How can you work it the distance travelled from a velocity time graphs?
By working out the area under a v-t graph
