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by Suhail Ahanger


Make a beam balance using cycle spokes, some thread and a couple of plastic bottles

Video Overview

    • Handle the cutter/scissors with care

    • If using the candle, light it with care and have an adult around

  1. You need two plastic bottles of the same size
    • You need two plastic bottles of the same size

    • Take a plastic bottle.

    • Cut the bottle in half using a paper cutter/scissor.

    • Repeat the above step for the other bottle.

    • Only the bottom parts of the bottle are needed for this TACtivity

    • The top part of the two bottles can be used later for "Balloon bugle " or " Cap Tiktiki" Tactivities.

    • Using the hole-puncher, make a hole 2cm from the top of the cut bottles.

    • You may also make the hole using a heated metal wire/spoke, which you can heat on a candle flame

    • You need to make 3 such evenly spaced holes along the top rim, so use your judgement to keep them separated by about 120 degrees

    • Take 3 threads of equal length (~25cm), and secure them with knots in each of the holes in the bottle

    • Repeat the above for the other bottle

    • The two bottles will now act as weight holders

    • Tie all the three threads together with a knot at the loose ends

    • Join the two spokes by screwing the spoke nut halfway into the threaded end of each spoke

    • Tie a thread to the centre of this spoke assembly

    • Use insulation tape near the thread to secure it firmly at the desired position.

    • Place the bottles at the extreme ends of the "beam" and use insulation tape to secure them.

    • Try to balance the two empty bottles.

    • If the beam is not balanced with empty bottles as seen in the picture, use layers of insulation tape at the extreme ends of the spoke as counter weights to balance the beam.

    • A balanced beam gives results with better accuracy.

    • The balanced beam can be seen in this picture.

    • Using the nuts given, play with your beam balance by trying various number combinations of nuts on either side

    • Weigh a nut using a scale and use the nuts to now calibrate weights of other objects

    • E.g., place a stone on one side of the balance and nuts on the other side. Measure the mass of the stone and record it here. Verify the mass by weighing it on a scale.

    • Make sure all three holes are at the same level of 2 cm from the cut end

    • The threads tied should be of the same length.

    • Make sure the bottles are hung at equal distances from the centre of the spoke beam.

    • When the thread is moved towards the holder end/balance point, will the balance get altered?

    • Weigh given balloon on a weighing scale, without inflating it, and record your reading here.

    • Now inflate the balloon and place it on one side of the balance. Balance it out by placing weight on the other side. Guess the mass of inflated balloon and record it here.

    • Now measure the mass of the inflated balloon on the weighing scale and record it here.

    • Is there any difference in measuring the mass of the inflated balloon with our beam balance and the weighing scale?

Finish Line

Suhail Ahanger

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