Question

Scenario

Carlos places a constant motion vehicle on the ground
and releases it so that the vehicle travels down the hall at
5 m/s in a straight line for 10 seconds.
Using Representations
PART A: Scale and label the axes on the graph to the right.
Draw a velocity vs. time graph of the constant
motion vehicle for the first 10 seconds of its motion.
Argumentation
PART B: Collect evidence about the physical meaning
of the slope of the graph that could be used to
support a claim. Fill in the blanks below.
Evidence: The slope of the velocity vs. time graph
is equal to
number
is also the unit
units
units
conds
for
physical quantity

Answer 1

A) The car started with a velocity = 5 m/s at time t = 0 seconds, and finish it path (that means its velocity = 0 m/s) at t = 10 seconds.

If we draw this two points: (0, 5) and (10, 0) we get a line, where x-variable represents time in seconds and y-variable represents the velocity of the car (see picture attached).

B) The slope of the plot obtained in point A is calculated as follows:

slope = (0 - 5)/(10 - 0) = -0.5

which represent the variation of velocity respect time, this is called acceleration. In this case, the acceleration is -0.5 m/s². The negative value indicates that the car is decreasing its velocity as time increase.

Answer 2

(a) Graph is attached

The velocity-time graph for the cart is attached.

On the x-axis, time is represented in seconds (s).

On the y-axis, velocity is represented in metres per second (m/s).

Since the cart travels constantly at 5 m/s, its velocity remains the same, so it is represented as a flat line, until a time of 10 seconds.

(b) The slope of the graph representes the acceleration

In a velocity-time graph, the slope of the graph represents acceleration (which is measured in metres per second square,
`m s^(-2)`). In fact, acceleration is defined as

`a=(\Delta v)/(\Delta t)`

where
`\Delta v` is the change in velocity while
`\Delta t` is the change in time.

In the graph, we see that
`\Delta v` corresponds to the increment in the y-variable, while
`\Delta t` corresponds to the increment of the x-variable; so acceleration is also equal to

`a=(\Delta y)/(\Delta x)`

which is the slope of the graph. In this particular case, the line is flat: this means that the slope is zero, so the acceleration is zero.