Step 1: Read the motion carefully.
The block moves at a steady speed of $6\ ms^{-1}$ and the surface has no friction. The question asks for the force the block presses onto the surface, not the sideways force.
Step 2: Note that horizontal motion does not matter here.
Constant speed means zero acceleration. Also the surface is frictionless, so nothing horizontal acts between block and ground. So the horizontal speed has no effect on the downward push.
Step 3: Look at the vertical direction.
In the up-down direction the block is in balance. Its weight pulls it down and the surface pushes it up with an equal normal force.
Step 4: Find the weight.
Weight is mass times gravity: \[ W = mg = 5 \times 9.8 = 49\ \text{N} \]
Step 5: Apply Newton's third law.
The surface pushes up on the block with $49$ N, so by the action reaction rule the block pushes down on the surface with the same $49$ N.
Step 6: State the answer.
The force exerted on the horizontal surface is: \[ \boxed{49\ \text{N}} \]