If I want to drag a box at a constant velocity across a table, and the force of friction is 150 N, how much force do I need to pull on the box with?

To get a constant velocity across a table, you need the net force on the box to be zero. So you need to apply a force with the same magnitude of friction, but in the opposite direction. So, the answer is 150 N.

concave lenses are used here. they spread the light out before it reaches the convex lens in the eye, therefore letting the image focus directly on the retina. hyperopia is known to you probably as farsightedness.

the pull of gravity on the rocket decreases