Kinematics How can uniform motion be expressed and how can it be calculated?
What is the difference between a vector and a scalar?
What is uniform acceleration and how can it be calculated?
How is instantaneous acceleration different and how can It be calculated?
What are the three different types of graphs and what do the different parts represent?
Uniform Motion I. Any object moving at a constant velocity II. When graphed, the line of best fit represents the average speed a. y = mx + b; where “m” is the constant (slope) and “b” is the initial value b. velocity = displacement / time (m/s) Vectors and Scalars I. A vector is a measurement that has a direction component a. Velocity and displacement are vector quantities (e.g. 5 km/h [S]) II. Speed and distance are scalar quantities (e.g. 15 m away) Uniform Acceleration I. Accelerated motion (non-uniform) occurs when an object travelling in a straight line changes its speed uniformly with time II. Non-uniform acceleration occurs when an object changes its speed in a non-uniform fashion III. Acceleration can be calculated (vector quantity) a. Average acceleration = change of velocity / time interval (m/s2) or can be = (final velocity) – (initial velocity) / time interval b. Instantaneous acceleration is the acceleration at a particular instant and can be found using tangent lines on graphs. This will appear as a curved slope on a graph Graphs I. Position-time graphs a. The slope of the graph equals velocity b. When the velocity is changing, the slope is a curve II. Velocity-time graphs a. The area underneath any section of the graph equals displacement b. The slope of the graph equals average acceleration II. Acceleration-time graphs a. The acceleration is zero when the motion is uniform b. Represented by a horizontal line when motion is non-uniform c. The slope equals the change in acceleration over time To draw a tangent, choose a point on the graph, and then draw a straight line that does not touch any other part of the graph
Uniform motion is motion at a constant velocity. * velocity = displacement / time * Uniform acceleration is when an object changes its velocity uniformly. * aav = Δv / Δt * or * aav = vf – vi / Δt * Instantaneous acceleration is the acceleration of an object at a certain instance during non-uniform acceleration; this can be found by drawing tangent lines and calculating the slope of the tangent. Position-time graphs, velocity-time graphs, and acceleration-time graphs can all represent those three quantities using slopes and shapes of the line or curve of best fit.
Kinematics What is acceleration due to gravity?
What are the five kinematics equations and when is it appropriate to use them?
What are vector scale diagrams?
What are the methods used to determine a resultant vector? How do you add and subtract vectors?
How is average velocity determined? What is relative motion?
Acceleration Due to gravity I. Earth’s gravity accelerates any free falling object at a constant rate of 9.81 m/s2 assuming negligible air resistance Kinematics Equations I. Each equation is to be used when 3 pieces of information have been given and the fourth is to be calculated. One variable will be omitted a. a = vf – vi / Δt b. Δd = vi Δt + ½ a Δt2 c. Δd = (vi + vf) Δt / 2 d. vf2 = 2 a Δd + vi2 e. Δd = vf Δt – ½ a Δt2 Vector Scale Diagrams I. When a vector arrow points in a direction that is not one of the 4 main directions (N, S, E, W), it is referenced by an angle from the closest main direction II. It is necessary to draw the size of your arrow to a certain scale like 1 cm = 1 km Adding and Subtracting Vectors I. To add, this is done head-to-tail and the resultant vector is the vector that connects the tail of the first vector to the head of the second vector a. When using a scale diagram, the resultant vector can be determined using a ruler and a protractor b. The resultant vector can also be determined using simple trig, trig laws, and the Pythagorean theorem II. To subtract, simply add the compliment of the second vector to the first; (compliment of a vector is the original facing the other way) Average Velocity and Relative Motion I. The average velocity can be determined by calculating the resultant displacement by the time interval: vav = ΔdR / Δt II. Relative motion can occur when there are various frames of motion like Walking on a boat, moveable walkways, swimming in a current, etc. a. The resultant velocities vary depending on the observer’s location b. A boat travels 25 km/h [S], man walks 5 km/h [N], then R = 25 -5, and the resultant velocity is 20 km/h [S]
Any object in freefall experiences an acceleration of 9.81 m/s2 (down), neglecting air resistance. There are 5 major kinematic equations: * a = vf – vi / Δt *, * Δd = vi Δt + ½ a Δt2 *, * Δd = (vi + vf) Δt / 2 *, * vf2 = 2 a Δd + vi2 *, and * Δd = vf Δt – ½ a Δt2 *. Vector diagrams can be drawn to scale and the resultant vector can be determined using a ruler and protractor. Another method is mathematics. Average velocity can be determined: * vav = ΔdR / Δt *. Relative motion can occur when there is more than one frame of motion.
