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A car start from the rest with an acceleration of 3 m/s2. Which velocity, in km/h, have after 7 seconds? Which is the travelled distance in meters?

**Solution with FisicaLab**

Select the Kinematic group and, inside this, the Particles module. Erase the content of the chalkboard. And add one element Mobile in X and one element Stationary reference system. As show the image below:

We know the end time, 7 seconds. Then in the element Stationary reference system write this.

**tf**7

To the element Mobile in X, we assume that the car begins its movement from the X coordinate 0 and at the time 0. Also, we assume that its movement is in the direction of the positive X axis. But, as we want the final velocity in km/h, we need write:

vf @ km/h

To the final velocity. As show below:

**Name**Car

**ax**3

**xi**0

**vxi**0

**ti**0

**xf**d

**vxf**vf @ km/h

Where *d* is the final X coordinate, an unknown data. To this example, the name of the mobile *Car* is irrelevant. Now click in the icon Solve to get the answer.

d = 73.500 m ; vf = 75.600 km/h ; Status = success.