Physics Chapter 3 Test:
Position- Time Graph
A graph of an object's position versus time
Velocity- time graph
A graphical plot of velocity (usually one component) versus time; may be used to evaluate displacement and accelerations during selected time intervals
Vector
A physical quantity that requires two pieces of information in order to be completely described -- a scalar value and a direction relative to a specified reference frame
Yes, although in some cases (running in a straight line), distance and displacement can be equal
Does distance often differs from the object's displacement?
Scalar
A quantity that can be completely described with only one piece of numerical information; a number that can be positive, negative, or zero
- 4.o km - 0.0 km
A student lives 2.0 km from his school. If he walks to school, turns around, and walks back home, what distance has he walked? What was his final displacement?
straight
A velocity-time graph has a ______ line.
Vector
Average velocity -- scalar or vector?
Vector
Change in position -- scalar or vector?
Magnitude
The absolute value of the measure of a quantity; the size of a measurement without regard to its direction or sign
Average speed in that time interval
The absolute value of the slope of any time interval on a position-time graph gives the object's ____
difference vector
The resultant of a vector subtraction operation
forward or backward
The sign go the velocity (slope) tells us if the object is moving ____ or _____, up or down, etc.
Vf = Vi + a(t)
Write the first equation of motion
d = vi (t) + 1/2a(t)²
Write the second equation of motion
d = vf²-vi²/2a
Write the third equation of motion
The instantaneous velocity vector
What vector has a magnitude equal to the instantaneous speed?
zero
A ball is thrown straight up in the air and falls down to the found. When the ball reaches its highest point (the instant before it changes direction and begins to fall) it velocity is_____
Vector
Acceleration -- scalar or vector?
Scalar Quantity
Any quantity that includes a number (with or without units only is a
Vector Quantity
Any quantity that includes both a magnitude (#) and a direction (can be a sin or a word) is called a
Vector quantities
Are vector or scalar quantities usually represented by bold variables?
Scalar
Change in time -- scalar or vector?
Vector
Change in velocity -- scalar or vector?
The motion is constant
Describe the motion of an object if its velocity-time graph is horizontal
(bold) d -- displacement |d| and (italicized) d -- magnitude of d, or distance
Discuss the differences, if any, between the one-dimensional quantities (bold) d, |d|, and (italicized) d
Vector
Displacement -- scalar or vector?
The average speed is the ratio of the distance traveled |x₂-x₁| over an interval of time (t₂-t₁) v=|x₂-x₁|/(t₂-t₁)
How would you determine the average speed of a trip to Grandma's house?
Scalar
Distance traveled -- scalar or vector?
The smaller the interval, the better the estimate because you measure the instantaneous speed at a given point by calculating the average speed of a small interval containing that point
How does increasing the number of data points on a position-time graph improve your ability to estimate instantaneous velocity at any point on the curve?
Position-time graph
If you graph the ordered pairs (t,x) for an object's position and time, what kind of graph is this?
-9.81m/s squared
In free fall, the acceleration is always
Scalar
Instantaneous speed -- scalar or vector?
uniformly accelerated motion
Linear motion in which acceleration during the time interval of interest is constant; motion in which the average acceleration equals the instantaneous acceleration
Uniformly accelerated motion
Motion in which the acceleration of an object is constant
meter/seconds
Si unit for velocity
Kinematics
The branch of mechanics that describe how systems move, without addressing what causes the motion
Dynamics
The branch of mechanics that mathematically describes the causes of motion
Displacement
The distance and direction between an object's position at one time and its position at a later time; in oscillatory motion, the distance and direction of the system from its equilibrium position
b
The slope of a position- time curve represents a- distance b- velocity c- displacement d- acceleration
d
The slope of a velocity- Time curve represents a- distance b- velocity c- displacement d- acceleration
Instantaneous speed
The speed of an object at a particular given time at that specific instant
free fall
The state of falling toward the earth or other planetary object under the influence of gravity only
Mechanics
The study of motion of macroscopic objects; the study of how (kinematics) and why (dynamics) things move
Velocity
The time rate of change in position in a specified direction
acceleration
The time rate of change of velocity
False. Displacement is positive only when the object has moved right (or up) from its initial position and it always give us both a number and directional information
True or False: Displacement is positive only when the object has moved left (or down) from its initial position.
False. Distance is always positive and it cannot give us information about the direction of movement
True or False: Distance can be positive or negative.
False. When working in 1 dimension at a time, represent vector quantities with italicized variables and subscript
True or False: When working in 1 dimension at a time, represent scalar quantities with bold variables and subscript.
True
True or False: Without a starting point (reference point, point of origin), we cannot prove that something has change position
False. Acceleration due to gravity is nearly constant at the earth's surface and is considered to be in the negative y-direction (pointing in the downward direction)
True or False: acceleration due to gravity is nearly constant at the earth's surface and is considered to be in the negative y-direction (pointing in the upward direction)
True
True or false: If speed is changing in an interval around that particular time, it isn't necessarily equal to the average speed on that interval and could be less than, greater than, or equal to the average speed for the interval
True
True or false: One dimension motion is represented on a number line
Valid for uniformly accelerated motion
Under what condition(s) is the first equation of motion valid?
Size of vehicle, initial speed, reaction time of the driver, road conditions (shape of road, surface material, and objects or substances on the surface)
What are some factors that affect stopping distance?
It describes how objects move
What does the study of kinematics describe?
Free fall
What is one common form of uniform acceleration?
Fundamental SI Unit: mole Unit Symbol: mol Formula Symbol: n
What is the Fundamental SI Unit for Amount of Substance?
Fundamental SI Unit: kelvin Unit Symbol: K Formula Symbol: T
What is the Fundamental SI Unit for Thermodynamic Temperature?
Fundamental SI Unit: kilogram Unit Symbol: kg Formula Symbol: m
What is the Fundamental SI Unit for mass?
Fundamental SI Unit: meter Unit Symbol: m Formula Symbol: d, r, s, l
What is the Fundamental SI notations for length?
Fundamental SI Unit: second Unit Symbol: s Formula Symbol: t
What is the Fundamental SI notations for time?
Object's displacement
What is the area under a velocity-time graph, bounded by a specific time interval, numerically equal to?
Average velocity
What is the displacement divided by the time interval called?
s=|x₂-x₁|+|x₃-x₂|
What is the formula for distance?
d=x₃-x₁
What is the formula for total/overall displacement?
The acceleration of an object
What kind of kinematic information is provided by the slope of a velocity-time graph?
Time interval, position, average acceleration, initial velocity, and initial position
What quantities must be known in order to find the displacement of an object using the second equation of motion?
Third equation of motion
Which equation of motion should you use if you do not know the elapsed time of an object's motion, assuming the necessary quantities are known?
a-
Which of the follow is a scalar quantity? a- distance b- velocity c- displacement d- acceleration
m/s squared
si unit for acceleration
displacement
the net change in position
Av. Velocity: V= x₂-x₁/ t₂-t₁: V= 25m-15m/ 8s-4s V= 10m/ 4s V= 5m/2s V= 2.5m/s V= 3m/s
use the data in the chart below to find the average velocity of an object over the interval t=4s to t-8s Time(s): Position(m) 0 5 2 8 4 15 6 20 8 25
