True
The electromagnet will become stronger if we add more coils because there are more field lines in a loop then there is in a straight piece of wire. In a solenoid there are a lot of loops and they are concentrated in the middle, as more loops are added the field lines get larger, therefore making the electromagnet stronger.
Your question has been heard loud and clear.
Averge velocity formula= Total distance travelled / total time taken.
Total distance=7meters
Total time taken=9 seconds.
Average velocity = 7/9= 0.77 metres/second
Average velocity= 0.77m/s
Thank you.