Fundamentals 5 Flashcards
What is determined from the area under a force vs. time graph?
impulse.
Write the equation relating torque to angular momentum.
Change in angular momentum equals (net)torque times time. (Usually written as delta-L = tau*t.)
Cart A moves east with momentum 30 Ns; cart B moves north with momentum 40 Ns. What is the magnitude of the momentum of the two-cart system?
50 Ns. (Momentum is a vector, so add the perpendicular components using Pythagoras.)
An object moves in a circle. What is the magnitude and direction of the object’s acceleration?
magnitude is v^2/r; direction is toward the circle’s center.
Write the standard kinematics equation for displacement.
displacement = v0t + (1/2)at^2.
How do you determine instantaneous speed from a curved position-time graph?
by taking the slope of a tangent line to the curve.
Under what conditions are the kinematics equations valid?
when an object has constant acceleration.
In a velocity v time graph with positive being right, if the line is under the horizontal axis which way is the object moving?
left. (The v-t graph is below the horizontal axis, which means motion in the negative direction, which is left.)
In a velocity v time graph with positive being right, if the line is under the horizontal axis and approaches horizontal zero, is the object speeding up or slowing down?
slowing down. (The vertical axis of the v-t graph is speed - the vertical axis values get closer to zero, so the speed gets closer to zero.)
In a velocity v time graph with positive being right, if the line is under the horizontal axis and approaches horizontal zero, what is the direction of the object’s acceleration?
right. (When an object slows down, acceleration is opposite the direction of motion. Motion is left, slowing down, so acceleration is right.)
