An evacuated tube uses an accelerating voltage of 67 kV to accelerate electrons to hit a copper plate and produce X-rays. How much voltage would be required to cause protons to reach the same speed an electron reaches? (We don't worry that the protons would be going in the opposite direction)

The of a machine determines its "usefulness." a. input force b. output force c. mechanical advantage

In a simplified model of the human eye, the aqueous and vitreous humors and the lens all have a refractive index of 1.40, and all the refraction occurs at the cornea, whose vertex is 2.60 cm from the retina. what should be the radius of curvature of the cornea such that the image of an object 40.0 cm from the cornea’s vertex is focused on the retina?

What is the speed of an object at a given moment?