Monday 28th – Bungee Cord Experiment
Saturday 2nd – Blanket Parachute Experiment

Monday 28th – Bungee Cord Experiment

This morning I was rooting around in the garage, looking for something to take apart, when I found a box of bungee cords. Dad used them to attach the cases to the roof rack of the car when we went on holiday last year. I hooked one between the workbench and a shelf and it was so springy that it catapulted a tennis ball right across the garage. Then I had an idea, if one bungee cord could fire a tennis ball across the garage, how far could I catapult something with all twenty tied together…..?

I took the box into the garden and started tying together the ends of the bungees. It took ages, but good scientists need to prepare their experiments well, so I didn’t mind too much. Eventually, I had one massive, long cord. I hooked one end round Mum’s favourite apple tree, and the other round the big cherry tree in the middle of the garden. This would be the best catapult in the world. I pulled it back as far as I dared; it was so stretchy that I almost reached the back fence, and so springy that it nearly pulled me over!

I was worried that the tennis ball would be too light, and that the bungees would fire it all the way to the house. If it hit the kitchen wall it might bounce off and go into next door’s garden. Our neighbours go out to work all day so I’d have to wait until after tea to go and ask for it back. I needed something that was heavier and wouldn’t go so far. Luckily, by the fence I found a stone that was almost as big as the tennis ball, and much heavier. That would be a better missile.

Next I needed a target, so I went back into the garage to look for something suitable. I found a piece of hardboard that was as tall as me, and an old three-legged table that used to be in the living room. I took them both outside, and by pushing the legs of the table into the lawn and leaning the board against it, I made my target. To finish it off I drew some circles on the board with a black marker pen.

Everything was ready. With the stone in my pocket, I picked up the bungee and walked backwards towards the fence. Soon the rope was off the ground and I could feel its springiness. I took the stone out of my pocket and hooked the cord round it. Holding the stone I slowly edged backwards towards the fence. The bungees began to creak and boing as they got tighter. The stone began to slip in my hands, so I gripped it firmly and lined it up with the target. I held my breath and let it go.

The cord twanged. The stone flew out of my hands. It arced through the air, straight towards the target, but it was too high! It sailed over the board and hit the kitchen window – SMASH! Mum came running out to see if I was alright. Then, when she knew I was fine, she started shouting at me and sent me up here to my bedroom to ‘think-about-what-I’d-done.’

Conclusion – I consider this experiment a success. The Bungee Catapult worked better than I had hoped. I managed to fire quite a heavy stone the whole length of the garden. I do have to stay in my room all afternoon, and Dad will tell me off some more when he gets home from work, but in a week, when it’s all forgotten I can sneak into the garage, find the bungees and try another experiment. I wonder if they’d make a good climbing rope?

To download free desktop artwork of the Bungee Catapult Experiment, click here

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Saturday 2nd – Blanket Parachute Experiment

I watched a programme about skydivers this morning. Some people jump out of a plane up to a mile in the air and the parachute helps them float safely to the ground!

After the programme I decided that I was going to try and make a parachute. I took one of the old blankets that Mum keeps in a box in the bathroom, and two lengths of rope from the garage. After laying the blanket out on the patio, I tied one end of the first rope to one corner, and then the other end of the rope to the next corner. I then did the same with the other rope on the other two corners. I hooked one arm into each loop of rope, and held the loops on each shoulder. As I ran down the garden the parachute filled up with air and I found it very hard to move forwards, but when I turned round, I found that it had caught on one of the branches of the cherry tree!

I untangled the blanket and ran back up the garden, away from the trees. The parachute billowed out and I nearly fell over. It worked perfectly. I saw dad watching me from the kitchen. He waved. I wanted to try out the parachute properly, so I piled up some bricks into a tower 50cm tall. I stepped up onto them carefully as they were a bit wobbly then jumped off. The parachute didn’t even move, it just lay on the ground. I thought that I should try a bigger jump, but there weren’t any more bricks in the garden. I couldn't see Dad in the kitchen, so I couldn’t ask him any bricks somewhere else. I checked the garage to see if he was in there. He wasn’t, but I did find the stepladders. They would be much better than a pile of bricks, less wobbly and much higher!

I took the stepladders into the garden and set them up on the grass, for a nice, soft landing. As I climbed up them they were very sturdy. Standing on the top step, I pulled the parachute up after me and bunched it up in my arms. I took a deep breath and jumped off, throwing the parachute up above my head. Half way down I felt the ropes pull under my arms as the parachute filled with air and I floated for about half a second. It had worked, but to float for longer I needed to jump from higher up.

I bundled up the parachute and ran upstairs to my bedroom. If I could jump out of my bedroom window I should be able to float down to the ground and that might take five seconds. As I opened my bedroom door I saw my dad standing by the window looking at me. He had his hands on his hips, and he was shaking his head. He made me put the blanket, the ropes and the stepladders all back where they belonged. Then he talked to me for hours about being safe and careful with my experiments. THEN he fetched his tools and screwed security chains onto all of the upstairs windows. Now they only open 15 cm unless you use the special key to undo the chain – which I’m only allowed to do if there is a fire in the house!

Conclusion – I consider this experiment a success. The parachute worked when I jumped off the stepladder, and if I could have jumped from higher up, I’m sure I would have floated down to the ground. My arms are quite sore from the ropes, though, so it may be better to tie the parachute ropes to my rucksack, which has padded shoulder straps.

To download free desktop artwork of the Blanket Parachute Experiment, click here

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