# Shared Flashcard Set

## Details

Section 1 Mechanical Equilibrium, AP Questions
Vector addition, subtraction and Mechanical Equilibrium
16
Physics
06/16/2012

Term
 What is a vector?
Definition
 A quantity that has both magnitude and direction.
Term
 What is the product of a vector multiplied by a scalar?
Definition
 V = vectork = scalark*V is A vector with a direction parallel to the vector and a magnitude equal to k times the magnitude of the vector.
Term
 How is a vector multiplied by a scalar algebraically?
Definition
 break up the vector into components, then multiply the components by the scalar. Example: nV = n (V (x-direction + V y-direction)
Term
 If two vectors, A and B, are added together, their resultant magnitude will be....."
Definition
 Break each vector into its components in the x and y direction. Then use the Pythagorean Theorem to determine the resultant vector's magnitude.
Term
 What is the resultant (magnitude and direction) of the vectors A = 5x and B = 8y
Definition
 magnitude = 9.458 degreesMake a triangle. Use the Pythagorean Theorem to get the magnitude. The angle is found using the tangent of the triangle. Angle = tan-1 (y/x)
Term
 Assume two forces are acting on an object. When will the magnitude of their resultant be the smallest?
Definition
 When the forces are acting in the same plane in opposite directions. The magnitude will be the difference between the two vectors. The angle between the two vectors will be 180 degrees.
Term
 To add two vectors graphically, which is used; the triangle method or the parallelogram method?
Definition
 Either one. Both are suitable for vector addition.
Term
 What is the resultant of the vectors A = 3x, B = -4y, and C = 2x + 7y
Definition
 5x + 3y
Term
 How is a vector resolved in terms of its components?
Definition
 By expressing it as the sum of the products of each of the components multiplied by the corresponding unit vector along the x- and y-axis, i.e., F = iFx + jFy. The vectors i and j are special unit vectors that lie along the x- and y-axis, respectively. The vector k is also sometimes used, as a unit vector that lies along the z-axis.
Term
 For a freely falling object in projectile motion, what is the acceleration in the x-direction?
Definition
 Zero. Gravitational acceleration has only a downward, constant x-axis component with a magnitude of g.
Term
 What is the acceleration in the y-direction for a freely falling body in projectile motion?
Definition
 a = -g = -9.8m/s2
Term
 What is the magnitude of a unit vector?
Definition
 A unit vector has a magnitude of one.
Term
 If a system of forces comes into equilibrium, it is said to be balanced by a single force called a (n)__________________.
Definition
 equilibrant. An equilibrant is a single force needed to bring an unbalanced system into equilibrium such that the net force is zero.
Term
 If a 1 kg mass falls through the earth's atmosphere with a constant velocity, the retarding force of the atmosphere must be equal to _________.
Definition
 9.8 N. Force acting on the mass is 9.8 N (W=mg; 1 kg x 9.8 m/x2); thus, if falling at constant velocity, the retarding force must be 9.8 N up.
Term
 What is meant by a rigid body being in static equilibrium?
Definition
 A rigid body is in static equilibrium when the sum of the forces and torques on it is zero.
Term
 What is the name of the quantity that has the units of kg m/s2?
Definition
 Newton
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