Chapter 2

Question 1

At rest

Answer 1

The condition of an object whose position is not changing

Question 2

Component of a vector

Answer 2

The scalar by which the unit vector must be multiplied to generate a given vector along the axis defined by the unit vector

Question 3

Displacement (delta r measured in meters (m))

Answer 3

A vector pointing from an object’s initial position to its final position: delta r = rf - ri

Question 4

Distance (d measured in meters (m))

Answer 4

A distance d between two points is a scalar equal to the absolute value of the difference in the x coordinates of those two points: d = abs(x1 - x2)

Question 5

Magnitude of a vector

Answer 5

A positive scalar associated with a vector. The magnitude of a vector in one dimension is equal to the absolute value of the x component of the vector: b = abs(b) = abs(bx)

Question 6

Position (r measured in meters (m))

Answer 6

A vector that specifies the location of an object along a reference axis. The vector runs from the origin to the location of the object and can be written as the product of the x coordinate of the object’s position and the unit vector i: r = x*i

Question 7

Scalar

Answer 7

A quantity that is entirely specified by a number and a unit of measure

Question 8

Speed (v measured in meters per second (m/s))

Answer 8

The average speed Vavg is a scalar equal to the distance traveled divided by the time interval it took to travel that distance. The instantaneous speed (or simply speed) is a scalar equal to the magnitude of the velocity: v = abs(v)

Question 9

Unit vector

Answer 9

A vector of magnitude one with no units used to specify a direction in space

Question 10

Unit vector notation

Answer 10

A mathematical representation of a vector, the product of a scalar and a unit vector: b = bx * i

The scalar bx is called the x component of vector b. The subscript x reminds you that bx is a signed number whose value depends on the choice of the unit vector.

Question 11

Vector

Answer 11

A quantity that requires a number, a unit, and a direction in space to be completely specified

Question 12

Velocity (v in meters per second (m/s))

Answer 12

A vector that gives the time rate of change in the position of an object. The average velocity over any interval is obtained by dividing the displacement during that time interval by the duration of the interval: Vavg = delta r/ delta t

The instantaneous velocity (or simply velocity) is the limit of the average velocity as the time interval goes to zero:
V = lim as t approaches 0 of delta r/delta t = dr/dt