When hockey players push the puck along the ice it slides causing heat which melts the ice causing the friction against the ice to be less.
When Jane is sliding down a slide, she is demonstrating translational motion.
If the desk doesn't move, then it's not accelerating.
If it's not accelerating, then the net force on it is zero.
If the net force on it is zero, then any forces on it are balanced.
If there are only two forces on it and they're balanced, then they have equal strengths, and they point in opposite directions.
So the friction on the desk must be equal to your<em> 245N</em> .
Time = (distance) / (speed)
Time = (4.12x10^16 m) / (3 x10^8 m/s)
Time = 1.37 x 10^8 seconds
Divide the seconds by 86,400 to get days. Then divide the days by 365 to get years.
Time = about 4.35 years
