"An ice skater applies a horizontal force to a

20.-kilogram block on frictionless, level ice,

causing the block to accelerate uniformly at

1.4 meters per second2 to the right. After the

skater stops pushing the block, it slides onto a

region of ice that is covered with a thin layer

of sand. The coefficient of kinetic friction

between the block and the sand-covered ice is

0.28.


Determine the magnitude of the normal force

acting on the block.