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Flashcards in C4 Terms Deck (86):
1

Mechanics

The scientific study of forces and motion. It consists of kinematics, dynamics and statics.

2

Kinematics

The science of describing how things move. It involves the measurements and calculations of position, time, velocity, acceleration, and displacement within a reference frame.

3

Dynamics

The study of how forces affect an object's motion. Based on Newton's 3 laws of motion.

4

Statics

The description of how stationary objects react to pushes and pulls.

5

System

Part of the universe under study separated from its surroundings by an actual or imaginary boundary.

6

Surroundings

Everything outside a system's boundary.

7

Frame of reference

The geometric space containing the reference point and coordinate axes from which a person observes or measures position and movement.

8

Coordinate axis

An imaginary line that contains an origin as a point of reference and is marked off in distance units.

9

Interval

A span of time during which a phenomenon is observed, calculated by subtracting the initial time from the final time. Always a positive number.

10

scalar

Any measurable property, represented by an italicized symbol, that can be completely described by a single piece of information. It can be either positive, negative, or zero. Includes volume, temperature, time and mass measures.

11

Vector

A measurable quantity, represented by a bold symbol (or a 1/2 arrow above the scalar symbol), that requires two pieces of information to fully describe it

12

distance

A positive scalar quantity representing the linear dimension a moving object covers during a time interval. It also may be the magnitude of displacement.

13

displacement

A vector quantity that describes the net distance and direction of motion. It is represented graphically by a vector arrow whose tail is at the starting point of motion and whose tip is the ending point.

14

magnitude

The size of any quantity expressed as a positive number in appropriate units.

15

speed

A scalar quantity that measures the rate of motion of a system. It may also be the magnitude of velocity.

16

average speed

The average rate of motion over a time interval that accounts for variations in speed. It is a positive scalar quantity.

17

Velocity

The vector quantity of the rate of displacement of a system or it can be described as speed in a given direction.

18

acceleration

The rate of change of the speed or velocity of a system during a time interval. It can either be a vector or scalar quantity.

19

What is mechanics the study of?

forces and motion

20

Who tried to explain motion by determining why things move?

Aristotle

21

The early Greek philosopher Aristotle tried to explain _______ things moved.

why

22

Galileo proposed that we study _______ things move before we conclude ________ things moved.

how
why

23

________ proposed that we study how things moved before we conclude why they move.

Galileo

24

________ is generally given credit as the pioneer in the modern study of mechanics.

Newton

25

Modern physics has divided the study of mechanics into what three parts?

kinematics
dynamics
statics

26

Which branch describes how things move?

kinematics

27

What is the branch of mechanics that describes why things move.

Dynamics

28

A system of reference points from which the position and motion of an object can be determined is referred to as the _______________________.

Frame of reference

29

What kind of quantities only have size?

scalars

30

Name some scalar quantities

temperature, mass, time, volume, density, length, area, speed, energy.

31

Things that have ______ as well as ________ are called vector quantities.

size
direction

32

Name some vector quantities.

velocity, force, momentum, position in space, acceleration

33

The _______ moved in a given ________ is called displacement.

distance
direction

34

Distance and displacement are identical quantities. (T or F)

F

35

Velocity and speed are the same. (T or F)

F

36

Speed in a specified direction is called __________.

Velocity

37

Distance divided by time defines ________.

speed

38

Displacement divided by time defines _______.

Velocity

39

Imagine that Bob ran around his school starting at the front doors. The total distance from start to finish in front of his school was 700 m. It took Bob 100 seconds to complete the run. What was his average speed? What was his average velocity?

speed–7 m/s
velocity–0 m/s (his displacement was zero)

40

Acceleration is the technical name for speed. (T or F)

F

41

The rate of change of velocity in a given time interval is called __________.

acceleration

42

A negative change in acceleration is called_________.

Deceleration

43

What is deceleration?

a negative change in acceleration

44

Can a car traveling cross–country have a constant velocity?

no. speed limits change often and stop lights and bathroom brakes interfere and disrupt your velocity.

45

Spatial

Describes something relating to or having the properties of space. 3 spatial dimensions - length, width, height.

46

Why are frames of reference important?

They determine how motion will be described.

47

What is the correct reference frame for a given situation?

In motion , no single reference frame is more correct than another.

48

What is best reference frame?

The frame that is most useful or makes the study of that motion easiest.

49

In physics, how is a system used?

A system helps to identify what factors must be taken into account in experiments and any scientific models developed.

50

Why are frames of reference important to the study of motion in physics?

They "anchor" observations and act as a landmark.

51

What is correct frame of reference for a given situation?

In motion, no single reference frame is more correct than another.

52

What is the best frame of reference?

The one that is the most useful or in which the study of that motion is easiest.

53

You're riding in an accelerating car that passes another car. What type of reference frame produces this kind of observed motion?

Accelerated reference frame

54

Three types of reference frames

Fixed reference frame
Accelerated reference frame
Rotational reference frame

55

Motion in a straight line, in 2 or 3 dimensions it is generally acceptable to use a ______ ______ frame in which the system of interest moves.

Fixed reference frame

56

When studying a system that revolves, it is often more convenient to choose an accelerated reference frame in which the rotating object and its axis are stationary. This is called a ________ _________ frame.

Rotational reference frame. It permits analysis of the pushes and pulls that cause the circular motion and the motions of other systems relative to the rotating system.

57

(T/F) The fact that one's point of view affects one's observations applies to many aspects of scientific investigation, including motion.

True

58

Continuum

Unbroken expanse or series.

59

What is another name for the magnitude of the velocity vector?

Speed

60

How many position coordinates are required to identify the position of a system undergoing 1 dimensional motion?

1

61

What symbol should you use to identify a system's position in one-dimensional motion?

x

62

What quantity does the formula for speed provided?

Average speed

63

Acceleration can occur if velocity changes _________, ___________ or both.

magnitude
direction

64

(T/F)Negative acceleration always means a system is slowing down.

False. Negative acceleration means that an acceleration is occurring in the negative direction of the coordinate system.

65

Contrast views of Greeks and scientists after Galileo & Newton.

4.1 Greeks - matter behaved in mysterious ways. After Galilieo/Newton, scientists observe how things move and then describe their motion with math.

66

How does kinematics differ from dynamics?

kinematics - how things move, dynamics - what makes them move.

67

A skier is schussing down a snowy slope. Describe everything that is part of the skier-system.

Jacket, snowpants, skis, poles, helmet, goggles, boots, gloves.

68

On a flight simulator game. What is the reference frame for the computer image?

The cockpit.

69

What evidence do we have that time began at creation?

Time began at creation. Gen 1:1

70

A vector quantity can be represented by a stylized arrow. How does this symbol represent a vector quantity.

The length of the vector arrow indicates the size of the scalar value and the direction the arrow points is the direction of the vector

71

When would actual distance traveled = the magnitude of a system's displacement?

The displacement and distance traveled are = when an object has traveled in a straight line in one direction between two points.

72

Explain why speed is a rate?

It compares the change in the value of a quantity in a certain span of time.

73

Explain why acceleration is a rate?

It is the rate of change of the speed or velocity during a given time interval.

74

What instrument displays the instantaneous speed of a car (the speed a car is moving at an instant in time)?

The speedometer.

75

What is significant about the sign of velocity in one dimensional motion?

It indicates the direction the objects are moving.

76

What kind of coordinate system is required to describe most real-world motion? Why?

Two and three dimensional motion.
Most real world motion occurs in these.

77

(T/F) In mechanics it is vital to understand how to measure motion before you try to understand the causes of motion.

True.

78

(T/F)When studying the motion of a thrown ball, the system is the ball and the hand that throws it.

True.

79

(T/F)The weather-vane on top of a barn measures the wind vector.

True.

80

(T/F) Position in a 1 dimensional requires only a single number.

True.

81

(T/F) The magnitude of -15.0 m/s is 15.0 m/s

True.

82

(T/F) * The instantaneous speed of a car must equal it's average speed at least once during a trip.

True.

83

(T/F) In most cases of motion, scientists try to avoid measuring velocities because it complicates measuring the data.

False.

84

(T/F) Increasing speed always indicates positive acceleration and decreasing speed always indicates negative acceleration.

False.

85

(T/F) Acceleration is the rate of change of the rate of change of position.

True.

86

(T/F) The definition of distances, displacement, speed, velocity and acceleration are the same in 1,2,or 3 dimensional coordinate systems.

True.