Chapter 2

Question 1

Motion

Answer 1

A very important topic to physics. Can be represented by a series of pictures. Or a series of dots.

Question 2

Kinematics

Answer 2

How things move: the relationships among distance, time, speed, acceleration, ect.

Question 3

Dynamics

Answer 3

What causes things to move and how much: force, impulse, momentum, ect.

Question 4

What does it mean if the dots are evenly spaced?

Answer 4

That means the object is moving at a steady speed.

Question 5

What does it mean if the dots are getting further a part?

Answer 5

The object is speeding up and if the dots are getting closer together the object is slowing down.

Question 6

Distance

Answer 6

How far the object is from a certain point (or how far it goes to get there). Magnitude only. Standard unit of measurments is meters.

Question 7

Position

Answer 7

Where an object is. It requires a reference point. Both magnitude and direction. Standard unit of measurments is meters. [Direction in Square Brackets]

Question 8

Scalar

Answer 8

Is a quantity that has magnitude only. - distance, speed, height, time, mass, energy. Represented by just a letter.

Question 9

Vector

Answer 9

Is a quantity that has magnitude and direction. - force, velocity, position, displacement, acceleration. Represented by a letter with a right-pointing arrow on top.

Question 10

Combining scalar quantities:

Answer 10

Dt = D1 + D2

Question 11

Combining vector with matching direction:

Answer 11

–> –> ->
Dr = D1 + D2
Magnitues simply add together algerbraically

Question 12

Component vectors

Answer 12

When two vector quantites are combined to prodcue a new vector.

Question 13

Resultant vector

Answer 13

Sum of two vector

Question 14

Scale drawing solution or “Tip to tail” method - Same direction

Answer 14

Method of adding vector. You draw the first vector(and label it), then draw the second vector with it’s tail at the tip of the fist vector. The resultant vector is then draw with it’s tail at the tail of the first vector and it’s tip at the tip of the second component.

Question 15

Vectors with opposite directions:

Answer 15

You can’t add two vector quantaties if they don’t have matching directions. Solution is to change the way one is expressed so that the directions match.
–> –> –>
Dr = D1 + D2
–>
Dr = ?
–>
D1 = 5m[E]
–>
D2 = 3m[W] : –> -3m[E]
–>
Dr = 5m[E] + (-3m[E])
= 2m[E]

Question 16

Scale drawing solution - Opposite directions

Answer 16

As long as motion is just a straight line so that the directions of the component vectors are the same or opposite, it is easy to draw. Just draw the second vector and the resultant vector beside the first vector to avoid drawing on top of each other.

Question 17

When motion is a straight line what do we do?

Answer 17

We often refer to one direction as positive and the other as negative direction. We don’t need to put arrows on the letter for this one because we are treating them more like scalars.

Question 18

How do we represent time intervals? Or how to find change in time?

Answer 18

Tf - Ti = delta (triangle) t

Question 19

Displacement

Answer 19

Change in position. Displacement comes from subtracting two vectors.
–> –> –>
detla D = Df - D

Question 20

To find the average speed of something:

Answer 20

Vavg = distance travelled/
time interval
= d / delta t
Units for speed = m/s
Speed is a scalar

Question 21

Velocity

Answer 21

–>
V
Units for velocity = m/s [direction in square bracets]
Velocity is a vector

Question 22

To find somethings average velocity

Answer 22

–>
Vavg = change in position(displacement) /
time interval
–> –> –> –>
Vavg = delta d = Df - Di /
delta t = Tf-Ti

Question 23

Difference between speed and velocity

Answer 23

Velocity has direction. If the motion is only in one direction, then the speed will be the magnitude of the velocity. There is a change of direction involved, then the magnitude of the displacement will be difference from the distance travelled, so the magnitude of the velocity will be different from the speed.

Question 24

What happens if the velocity is constant?

Answer 24

The velocity at any time will equal the average velocity.
–> –>
V = delta d /
detla t

Question 25

Cycle

Answer 25

When an object makes repeated motions, one complete motion is a cycle. This is just a count, has no units.

Question 26

Period of repeated motion

Answer 26

The time required for one cycle. Symbol - 𝘛Units : seconds

Question 27

Frequency of the repeated motion

Answer 27

The number of cycles in one second. Symbol : 𝘧
Units: Hz (hertz)
Hz is equal to 1/s or s^-1 since cycles are not actually units.

Question 28

Why are frequency and periods reciprocals of each other?

Answer 28

Since the units for period and frequency are recipricals.
𝘧 = 1/T
or
T = 1/𝘧

Question 29

On a graph what does the slope of the line joining the starting and ending points represent?

Answer 29

The constant velocity that would take the object from the starting point to the ending point in the same amount of time.

Question 30

The formula for average velocity rearranged for final position :
–> –> –>
Df = Vavg x delta t + Di
What does this formula match to and how dos it relate to a graph of motion?

Answer 30

Exactly matches to
y = mx +b. Vertical intercept is Di, delta
t (horizontal value involved) = x, and slope is Vavg. Vertical value at the end of the time interval is Df.