Consider the following systems: i) water behind a dam; ii) a swinging pendulum; iii) an apple on an apple tree; iv) the space shuttle in orbit. in which of the systems is potential energy present? 1. i, ii, iii and iv 2. i, ii and iii 3. i and ii 4. ii, iii and iv 5. ii and iv

1, 2 and 3

Explanation: Potential energy is "stored energy of the system" so let's analyze each system and see if it has some way of creating energy.

1) The dam is containing the water, and if we open a little hole in the dam (or remove the dam) the water will move because the force of gravity, so there is energy stored, and this means that this system has potential energy.

2) the singing pendulum is already moving, if the pendulum is in the lowest point (where the velocity is the biggest) it has only kinetic energy, if the pendulum is in the highest position (where it changes the direction of movement, which means that at this point it has zero velocity) has only potential energy. In all the other points, it has both, potential and kinetic.

3) The apple is being held by a stem, if we remove the stem, it will fall to the force of gravity, so this has potential energy.

4) The mean that it is in orbit, means that it is in equilibrium, so it moves at a constant velocity and is held in place only by the gravity, so this has no "wall" holding it. There is no potential energy in the system.

a and b sometimes have a positive value