(really need will give branliest)
read the following list of objects:
the water behind a dam, a fully wound watch spring, a swing moving back and forth, an object moving on earth's surface, a roller coaster cart when it hits the lowest point of the track
which statement is correct?
a swing moving back and forth and the water behind a dam have only kinetic energy.
a fully wound watch spring and a swing moving back and forth have only potential energy.
the water behind a dam and a roller coaster cart when it hits the lowest point of the track have only potential energy.
an object moving on earth's surface and a roller coaster cart when it hits the lowest point of the track have only kinetic energy.

An charge with mass m and charge q is emitted from the origin, (x, y)=(0,0). a large, flat screen is located at x=l. there is a target on the screen at y position y(h), where y(h) > 0. in this problem, you will examine two different ways that the charge might hit the target. ignore gravity in this problem. 1.assume that the charge is emitted with velocity v(0) in the positive x direction. between the origin and the screen, the charge travels through a constant electric field pointing in the positive y direction. what should the magnitude e of the electric field be if the charge is to hit the target on the screen? express your answer in terms of m, q, y(h), v(0), and l. 2.now assume that the charge is emitted with velocity v(0) in the positive y direction. between the origin and the screen, the charge travels through a constant electric field pointing in the positive x direction. what should the magnitude e of the electric field be if the charge is to hit the target on the screen? express your answer in terms of m, q, y(h), v(0), and l.

What are the differences and relationships between speed, velocity, and acceleration

The earth's magnetic field, with a magnetic dipole moment of 8.0×1022am2, is generated by currents within the molten iron of the earth's outer core. suppose we model the core current as a 3000-km-diameter current loop made from a 1000-km-diameter “wire.” the loop diameter is measured from the centers of this very fat wire. to decide whether this is a large or a small current density, compare it to the current density of a 7.0 a current in a 2.0-mm-diameter wire.