Aforce of 60. newtons is applied to a rope to pull a sled across a horizontal surface at a constant velocity. the rope is at an angle of 30. degrees above the horizontal. determine the magnitude of the frictional force acting on the sled. [1]

For this case, the friction force acting on the sled will be of the same magnitude as the horizontal component of the force that is being applied at 30 degrees above the horizontal since the velocity is constant. Therefore, the result will be given by:
 F = 60 * cos (30) = 51.96N
 the magnitude of the frictional force acting on the sled is 51.96 N

Mendeleev predicted the atomic mass of each element along with compounds they each should form.

Explanation:

Based on other elements in the same group he predicted the existence of eka-aluminum and eka-silicon, later to be named gallium (Ga) and germanium (Ge).