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HELUS8CH1
8th grade physical science: chapter 1: Motion
| Question | Answer |
|---|---|
| A ___ is a starting point used to describe the position of an object. | reference point |
| The ___ is the direction you must travel from the reference point toward an object. | reference direction |
| Units like ___ (m), kilometers (km), and centimeters (cm) are used to describe distances. | meters |
| To describe an object’s position, you must include three pieces of information: a reference point, a reference direction, and the distance from the reference point in the ___. | reference direction |
| Positive (+)and ___ (-) measurements of distance are often used to describe positions | negative |
| ___ measurements are usually in the reference direction, or toward the object from the reference point. | Positive |
| Negative measurements are usually in the opposite direction from the reference direction.Negative measurements are usually in the ___ direction from the reference direction.They start from the reference point and measure away from the object | opposite |
| One way to describe the position of an object is as an ___ pointing from a reference point toward the object | arrow |
| A ___ is a quantity that has both a size and a direction | vector |
| Vectors are often drawn as ___ pointing away from a reference point in the referencedirection. | arrows |
| ___ is one example of a vector. | Position |
| The length of a position vector is the ___ from the reference point to the object whose position the vector represents | distance |
| Maps have two ___, east-west and north-south. | reference directions |
| A two-dimensional map can be drawn as a graph used to represent the location of objects with two ___ | reference directions |
| East is usually on the positive ___, and north is usually on the positive ___. | x-axis. y-axis |
| A location must be chosen to be the reference point, or ___, of the graph. | origin |
| ___ is the difference between the initial position and the final position of an object. | Displacement |
| Displacement is measured as a distance from a reference point in a particular direction, and so displacement is a ___. | vector |
| A ___ measures the change in one quantity in a particular length of time | rate |
| ___ is the rate of change of position over a period of time | Speed |
| An object that moves at a ____ travels the same distance each and every second | constant speed |
| ___, or the speed of an object at a specific instant of time, is especially useful to measure for objects whose speed changes. | Instantaneous speed |
| An object’s ___ is its total distance traveled divided by the total time it traveled | average speed |
| The equation for average speed is average speed = total distance divided by ____. | total time |
| If you know any two quantities in the average speed equation, you can use the equation to calculate the ___. | third |
| The unit for speed is a ___ unit divided by a time unit. The SI unit for speed is ___ | distance, m/s |
| ___ is a measurement of both the speed and direction of motion of an object | Velocity |
| Velocity is a ___. It has both a size (the speed of the object) and a direction (the direction the object is moving) | vector |
| Speed is different from ___ because speed does not include the direction in which the object is moving | velocity |
| ___, another vector, is the rate at which velocity changes over time | Acceleration |
| When an object speeds up, the direction of its ___ is the same as the direction of its motion. | acceleration |
| When an object ___, its acceleration is in the opposite direction from the direction of its motion | slows down |
| When an object changes the direction in which it is moving, its velocity changes. This means that it is ___ | accelerating |
| On a position-time graph, ___ is usually plotted on the y-axis and time is usually plotted on the ___. | position, x-axis |
| The ___ of a line is the steepness of the line. | slope |
| On a position-time graph, an object’s speed can be determined by looking at the ___ of the line that represents that object’s motion. | slope |
| On a position-time graph, the steeper the slope of a line, the ___ the object was moving. | faster |
| On a position-time graph, the flatter the slope of the line, the ___ the object was moving | slower |
| The vertical change, or change along the y-axis, on a graph as an object moves between two points is sometimes called the ___. | rise |
| The horizontal change, or change along the x-axis, on a graph as an object moves betweentwo points is sometimes called the ___ | run |
| The ___ of a line can be calculated by dividing the rise between two points on the line by the run between the same two points | slope |
| Only objects moving at ___ speeds have straight line position-time graphs | constant |
| The average speed of the entire trip of an object that does not move at constant speed can be calculated by finding the slope between the ___ and ___ data points on the graph of the object’s motion. | starting, ending |
| If a ___ graph has a horizontal line, the object whose speed the graph represents was moving at a constant speed. | speed-time |
| If an object speeds up, its line on a speed-time graph curves up to the right. The steeper the slope, the faster its speed is ___. | increasing |
| When an object ___, its line on a speed-time graph slopes down to the right | slows down |
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jnosik
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