• Question: How many rolls of cellotape would it take to stick someone to the ceiling. I was thinking of trying it. I had a go with my cat but unfortunatly sacrafices must be made for science.

    Asked by clarkerl04 to Amelia, Jim, Liz, Prateek, Richard on 13 Jun 2011. This question was also asked by gibsonol02.
    • Photo: Amelia Markey

      Amelia Markey answered on 12 Jun 2011:

      LOL!!! I hope your cat is ok…

      I’ve got to be honest I have absolutely no idea. Would be really fun to try it! That’s the thing with science, sometimes you haven’t got a clue and you just have to keep trying things out until you get the answer. I’d also like to cover the ceiling with velcro, put a velcro suit on and see how long you could stay there before you drop down on some unsuspecting person walking by!

    • Photo: Jim Caryl

      Jim Caryl answered on 12 Jun 2011:

      Ha, well, I’ve got no idea either! But I’ve never let not knowing something get in the way of wanting to try something; it would actually be possible to work out, or at least get to near the right number.

      Imagine how long a strip of tape you’d need to go from the left-side to the right-side of a person, but also extend some distance to either side. Then half-way along the strip, try securing objects of increasing weight. When you find one that can’t be held by the strip of tape, weigh it on the weighing scales. Then you just need to work out how many times that weight goes into the weight of the person you’d want to sellotape to the ceiling, probably quite a lot, but whatever number that is will be the number of strips you’d need; if you know the length of the strip, then you can work out how much sellotape you’d need as most sellotapes tell you how long they are.

      You could also work out how much ‘stick’ there is in every 2.5 x 2.5 cm square (square inch) of sellotape, using a similar method to above, checking different weights, but all must only be stuck onto a 2.5 x 2.5 cm square. Once you know how much weight a 2.5 x 2.5 cm square will hold, you can work out how many squares (the ‘area’) that would be needed to hold the weight of a person – I’m betting this area would be more than you could fit on a person, so this tells you about how far each side of the person the tape would need to extend.

      You’d have to try different variations of whether you go from side-to-side or criss-cross with the tape, and you’d have to ensure that the ceiling was of a material that you can stick things to.

      In any case, that’s two ways of working it out, I’m sure there are better (I’m no physicist – try asking one), but I don’t recommend trying it with your cat (poor cat!), or a person; I’m also pretty sure it’d pull the wallpaper off the ceiling, so I don’t think your folks would be pleased. Sometimes it’s just fun to figure these things out ‘in theory’, it’s what we call a ‘back of the envelope calculation’.

    • Photo: Richard Badge

      Richard Badge answered on 12 Jun 2011:

      Hi clarkerl04 (I’m guessing you did not choose that username),

      Jim’s answer is great – you could certainly get a long way to working how much weight a given amount of sellotape could hold, and its certainly got a lot to do with the area required and the amount of stickiness…

      Looking into this I came across this great website about animal sticky feet (no, wait there is a sellotape connection….)

      On the site they explain how gecko’s feet work so that they can walk on walls (not just stick to them, but also unstick their feet fast enough to run!). There is also a section on adhesive tape that explores another factor I had not thought about: How strongly adhesive tape sticks is dependent upon the pressure applied when it sticks – more pressure pushes the sticky stuff into the bumps on the surface, giving a larger effective surface area and so a stronger bond…

      Who knew that the science of sticky tape was so complicated!


    • Photo: Lizzard O'Day

      Lizzard O'Day answered on 13 Jun 2011:

      Hmm just an estimate but at least 8-11 (depending on the size of the person). Also, I recommend listening to Flight of Conchords “Sello Tape” song for mood music. Good luck and god speed to the cat!

    • Photo: Prateek Buch

      Prateek Buch answered on 13 Jun 2011:

      hahah I like your attitude – although I’m not sure your cat would agree :-).

      As others have already commented, this is the sort of question that gets science going – and the fun isn’t just in finding out the answer, it’s in designing, carrying out and analysing a good experiment that allows you to get an answer.

      BTW maybe you’d be better off using velcro as Amelia suggests…?!