Probably worn steering and/or suspension parts. Have the front end safety inspected.
At moderate speeds, yes. For higher speeds or tight cornering, you might be causing a problem.
yes they would. you my be able to reduce the problem by having the wheels computer balanced. you may be able to have the wheels straightend or replaced
You can't convert between seconds, and meters/second. If you have a problem that involves speeds, use the formula: distance = speed x time.
Tires/wheels out of balance?
Alignment
why is my 1991 Mazda truck surging at higher speeds
Most likely its your tires. Could just need balanced. Or you might have uneven wear making it shimmy.
Despite repeated balancing, my 2004 and 2007 Ford Focus (Foci?) would shimmy at speeds above 65. In both instances the problem was rectified by the installation of new sway bar end links (Google it). Any decent auto parts store will have them for about $25 each (you need 2) and most DIYers will have the metric sockets and wrenches necessary to install.
Higher g's produced at higher speeds are harder to survive.
Because your motor is spinning faster at higher speeds causing higher rpm's
Despite repeated balancing, my 2004 and 2007 Ford Focus (Foci?) would shimmy at speeds above 65. In both instances the problem was rectified by the installation of new sway bar end links (Google it). Any decent auto parts store will have them for about $25 each (you need 2) and most DIYers will have the metric sockets and wrenches necessary to install.
Highly variable, but in inclement conditions at higher speeds a pro would be looking 20-30 seconds ahead a lot I think the book answer is at least ten..