Swings work in the same way a pendulum works. At one end there is a mass being held up by something like a rope, string or wire but in this case chains. The mass is you sitting on the seat. You push yourself forward and backward to gain momentum and then start swinging. At the peak of your swing where you stop and fall in the opposite direction, you have full Potential Energy and no Kinetic Energy. In the middle of your swing you have full Kinetic Energy and Potential Energy. In between the peak and the middle of your swing you have half of both Kinetic Energy and Potential Energy (see diagram below).
A slide is simply a smooth inclined plane. When you sit at the top of a slide, gravity is pushing down on you. The slide is holding you up so gravity isn’t pushing you straight down to the ground at 9.8 metres per second (m/s2.) Gravity is instead pushing you down the incline of the slide. The speed you go down a slide depends on the incline of the slide. The steeper the slide the closer you are to the 9.8 m/s. For example you could hit the earth at the bottom of the slide at 7 m/s for a steep slide or at 4 m/s for a less steep slide. The speed you go down a slide depends on friction. If you are wearing pants made of nylon, the friction between you and the slide will be much less so you will go a lot faster. If you are wearing pants that create lot of friction between them and the slide, you will move very slowly and possibly even not move at all.
A seesaw is a simple first class lever with the load at one end and the effort force at the other and the fulcrum in the middle. On a seesaw the people involved go up and down. When the person is higher he becomes the effort and the person who is lower becomes the load (see diagram below).
When the person who was once higher becomes lower he then becomes the load and the person who was once lower becomes higher and is the effort force (see diagram below).
This continues until the two people involved stop using the seesaw.
In a rocking horse, the spring stores Elastic Potential Energy in the way that when you pull back on the handlebars, you are stretching the spring out of its normal shape as much as you can. When the spring goes back into its normal size, it pushes forward into its normal position and then the mass of you pushes you forward causing the spring to stretch and then the spring goes back into its normal position. The mass of you then brings the horse back and so on until it stops which is when you start over again by pulling back on the handlebars.
