Large vehicles need more room to make turns. when you approach an intersection and see a truck ahead signaling a right turn, you should stay next to the truck, close to the curbside, until the turn is completed.

This statement is false.
The correct statement would be,
"When you approach an intersection and see a truck ahead signaling a right turn, you should stay behind the truck, away from the curbside, until the turn is completed."

Larger vehicles require a larger space to turn, being next to the truck and close to the curbside will only make it more difficult for the truck driver to complete the turn. This in turn will waste more time or even block traffic while the truck driver tries to complete the turn in the difficult situation that could have easily been avoided.

The actual answer is c force stays the same while direction changes

To find speed, or mph, use distance/time.