Question

SURFACE TENSION. You can make a needle float, even though the needle is heavier than water. Obtain a large, flat pan of water. Carefully, on the water’s surface, lay out a SINGLE-PLY (thickness) of double-ply toilet paper. Gently ease a needle onto the paper, keeping the needle level. Using a fork, slowly press down on the toilet paper to sink the paper out from under the needle. (Do not touch the fork to the needle.) It may take a few tries, but the needle should remain floating, even though it is heavier than water. There is a “skin” of tightly packed water molecules on the surface of the water. Soap will disrupt this skin of surface tension. Using your finger, gently introduce a tiny amount of dish soap onto the water. What happens to the needle? Describe exactly what you did and what happened:

Answer 1

When needle is carefully placed on s placed Water Sur Water surface behaves like a stretched en elastic membrane. " When the needle Surface the cohesive between lue water molecules on vis challenged. on the lhe surface एक " The cohesive force is strong enough that the needles weight and resulting does not the water molecules. As a result the needle flea But to pa fleats, But of the same needle 5 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 4

So cohesive fo sinks. is placed vertically be pressure is due lo less surface area. resulted force So be needle Now bo is added detergent I then the Surface bensions reduced. is not possible for the water the needles weight the Saap water 2013 balance