2 Steps for solving physics problems List your givens and what you are looking for.Narrow down what type of problem it is (momentum, constant acceleration, etc.)Look for the equation that you will ultimately need to solve the problem and see if you need to find any other variables first.Reread the problem to make sure you didn’t miss any key points or terms.Solve.
3 Graphs rise = Δy-axis run Δx-axis The AP loves graphs, most of which we will never specifically look at, so be prepared to interpret and create graphs.The x-axis is the independent variable (the one you control) and the y-axis is the dependent variable (the one affected by the independent variable).Time is almost always an independent variable.Remember that the slope of a line isrise = Δy-axisrun Δx-axisIf a graph is a parabola, you can square the numbers on the x-axis to create a linear relationship
4 Speed and Velocity v = x – xo = Δx t – t0 Δt There is a difference between average, final, and instantaneous speed/velocity.With average speed there is no acceleration involved. The initial and final speed are the same__ v = x – xo = Δxt – t ΔtWith final speed, you usually need to use one of the constant acceleration equationsWith instantaneous speed, it is the speed at that exact instant. This can be you final speed, your initial speed, or any other point in time.
5 Acceleration a = v – v0 = Δv t – t0 Δt Acceleration is the change in velocityThe speed or the direction can changea = v – v0 = Δvt – t0 ΔtIf the sign (+ or -) of the acceleration is the same as that of the velocity, the object is speeding up.If the sign of the acceleration is the opposite of the velocity, then the object is slowing down.
6 Constant acceleration v = v0 + atx = ½ (v + v0)tx = v0t + ½ at2v2 = v02 + 2axYou can only use a=-10m/s2 if the object is in free fall. If not, you can’t use this acceleration.If no acceleration (or change in speed) is mentioned, but you see a velocity, you will most likely need the average velocity equations
7 ForcesAs soon as you see something about forces in a problem, draw a FBD.Weight (mg) is ALWAYS straight downNormal force is ALWAYS perpendicular to the surfaceIf there is no acceleration (object at rest or moving at a constant velocity), then the net force in that direction is zero.If a=0 in a direction, then ΣF=0 in that directionUps=downs; lefts=rights
8 Forces SI Unit of Force: kg x m/s2 = newtons (N) 3 laws of motion Law of inertia (there are no forces here because there is no acceleration)ΣF = maLaw of action and reaction (this law involves
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