Liang hit a tennis ball making angles 45∘ and 60∘ with the horizontal, with the same total speed as shown below. Which launch angle causes the ball to travel further horizontally before hitting the ground?

The horizontal blue line through the middle of the lens is called the optical axis. as the lamp is moved above or below the axis, keeping the horizontal distance to the center of the lens constant, how does the horizontal distance from the lens to the image change?

The flow of electrons from one atom to another is called

How does the strength of the electrostatic force between an electron and a proton compare to the strength of the gravitational force between them?