Question

Use the graph for both answers.

At what time would the magnitude of the velocity reach 36.00 km/hr?

A. 6.00 sec
B. 36.00 sec
C. 208.00 sec
D. It is always the same, traveling at 36.00 km/hr.

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This graph depicts an object that has _____.

A. positive acceleration
B. constant velocity
C. negative acceleration
D. no acceleration

Answer 1

First one is 6sec
The second one is positive acceleration

Answer 2

1. A. 6.00 sec

The graph shows the velocity of an object (y-axis) versus the time (x-axis). In order to find when the magnitude of the velocity reaches 36.00 km/h, we should find the time t (x-coordinate) at which the velocity (y-coordinate) is 36.

By looking at the graph, we see that this occurs when t=6.00 s.

2. A. positive acceleration

In a velocity-time graph like this one, the slope of the curve corresponds to the acceleration of the object. In fact, acceleration is defined as:

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

where
`\Delta v` is the variation of velocity and
`\Delta t` is the variation of time. We see that this quantity corresponds to the slope of the curve in the graph (in fact,
`\Delta v` represents the increment of the y coordinate, while
`\Delta t` represents the increment of the x coordinate). So, a positive slope means a positive acceleration: in this case, the slope is positive, so the acceleration is also positive.