For formulation you can do something like this (please see attached picture below, in this case I have assumed that you are giving velocity in x direction. For other corresponding direction, please use the formula tab for that respective direction): 40t(t<=10)+400*(t>10)
Note: if your velocity is in km/h then you have to convert it to m/s as SimScale uses SI units for all cases. If this velocity value is in m/s then you may have to reconsider it as it is a high velocity which is not easy to simulate.
you can upload a .csv file in table upload option, please have a look at the documentation here.
In your case, the file data will look something li`ke this in case you want to give velocity only in x direction (with comma delimiter):
time,velocity in x,velocity in y,velocity in z <-- you can ignore this first line in your file
The second row is just on a safe side. If you have used ‘Out of bound’ as Clamp then you can ignore this row since clamp will fix the value after 10 seconds.
I hope this helps. If you have any question/s, feel free to ask.