Spring Scale Calibrated with Known Weights

A spring scale, or newton meter, is a spring fixed at one end with a hook at the other. By Hooke's law the stretch grows in step with the force, so the marks on its scale are evenly spaced. This one is built in a clear tube with a paper scale and calibrated with known weights: on Earth a 100 g mass pulls with about 0.98 N (100 g × 9.81 m/s²). The sizes here are ours: a tube about 20 cm long and a light extension spring that stretches clearly under 1 kg. Do not load it past the heaviest calibration weight: an overstretched spring stays longer and the scale is lost.

初心者

2 hours

手順

Make the hooks

Bend two pieces of steel wire with round-nose pliers: one with a loop at each end to hang the spring from the top plug, one long rod with a loop at the top and a hook at the bottom.

このステップの材料:

鋼線0.4 m

必要な工具:

丸口ペンチ

Plug the tube

Push the top wire through one cork disc and glue the disc into the top of the tube. Make a hole in the second disc for the rod to slide through and glue it into the bottom.

このステップの材料:

アクリル管（透明）1 個

小さなコルク円板2 個

瞬間接着剤（シアノアクリレート）1 個

必要な工具:

クラフトナイフ

Hang the spring

Hook the spring to the top loop and the rod's top loop to the spring, so the rod hangs out through the bottom plug. The lower end of the spring is the pointer.

このステップの材料:

引張ばね1 個

Fit the scale

Glue a strip of graph paper along the outside of the tube and mark zero at the spring's lower end with nothing hanging.

このステップの材料:

方眼紙1 個

必要な工具:

油性マーカー

Calibrate

Hang 100 g, 200 g and so on up to 1 kg, marking the pointer each time; each 100 g is about 0.98 N. The marks should be evenly spaced; check that the pointer returns to zero when unloaded.

必要な工具: