Unit 1: One-dimensional Motion

vector

has a magnitude/ size and a direction

scalar

only has a magnitude/ size

speed

distance/time

is speed scalar or vector

scalar

velocity

speed and direction (distance, time, and direction)

is velocity scalar or vector

vector

give an example of scalar vs vector

5m is scalar (distance), +5m is vector (displacement, distance with a direction)

look over reference frames

importante

what is displacement

change in position

what is the formula for displacement

change in X\= Xf- X0

which axis is X

horizontal

which axis is y

vertical

which axis is z

3rd axis

is displacement vector or scalar

vector

t/f distance b/w two objects is not the same as distance traveled

true

is distance traveled a vector or scalar

scalar (no direction)

Distance is really another name for what

magnitude or size of displacement

describe what happens if an object changes direction in its journey

total distance traveled will be greater than the magnitude of the displacement between the two points

what is confusing about displacement

distance traveled can be greater than displacement

instantaneous speed

speed at a particular moment in time (magnitude of instantaneous velocity)

instantaneous velocity

velocity at a particular moment in time (speed and direction) \-- you'll need to use a smaller displacement to find this, and will likely need to use an integral

t/f instantaneous velocity and average velocity are the same thing

false!

what is one thing that can give instantaneous velocity in certain situations

slope

large displacement over a small amount of time is what

a large velocity

average velocity

change in a position divided by the factor of time of travel

why is velocity a vector

because displacement is a vector (magnitude and direction)

t/f avg velocity does not tell us anything about what happens between the starting and ending point

true

speed, having no direction is considered what

scalar

the magnitudes of instantaneous speed and velocity are always \_____ but the magnitude of avg speed and avg velocity can be \_______

the magnitudes of instant. speed and instant. velocity are always identical, but the magnitudes of average speed and average velocity can be very different

because distance traveled can be greater than the magnitude of displacement, the average speed can be greater than

the magnitude of the average velocity (example in notes)

why is average speed not the magnitude of average velocity

because displacement can be zero (if the trip is out and back)\-- making avg velocity zero, but the speed would not be zero

what does the vertical axis represent in a position vs. time graph

position of an object

what is a common mistake made when looking at position vs. time graphs

the line is interpreted as the path of the object in space, it doesnt represent that, it represents the position (changing placement)

what does the slope on a position vs. time graph represent

the velocity of an object

what does the slope at a particular time on a position vs. time graph represent

instant. velocity

how is the object moving when slope is positive and velocity is positive

the object is moving the positive direction

when slope is negative (downward), and velocity is negative which direction is the object moving

the object is moving in the negative direction (possibly backwards)

when slope is zero (line of slope is horizontal), and velocity is zero what is happening with the object

the object is momentarily at rest

the expression/ equation for slope is the same as

velocity [ x2-x1/t2-t1]

why does it make sense that the equation for slope is the same as the equation for velocity

because velocity is change in position/ time

the slope of a position graph at a given moment in time gives

instantaneous velocity at that moment in time

t/f instant. velocity does not have to equal avg velocity

true

at what point is instant. velocity equal to avg velocity

if the slope is constant, then the instant. velocity will equal the avg velocity between the two points where it is constant

what does curvature on a position graph mean

if a position graph is curved, the slope is changing (means that velocity is changing and implies acceleration)

in sum, curvature in a graph means

an object is accelerating, changing in velocity/ slope

change in velocity is determined by \______ on a graph

change in slope (can't necessarily know by looking at the graph, need to determine the slope)

what denotes negative acceleration on a graph

slope goes from positive to negative (upside down bowl)\--- it's negative that your food falls out

what denotes positive acceleration on a graph

slope goes from negative to positive (rightside up bowl) \-- positive if all your food stays in your bowl

what does it mean for acceleration if velocity is constant

acceleration is zero