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

(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, ). In fact, acceleration is defined as

where is the change in velocity while is the change in time.

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

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.

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.