1 Prov ing that a hy pothesis is fa lse What i f an ex per iment proves that the hy pothesis is fa lse? Then you have to ma ke a new hy pothesis and test it . For example, ta ke t wo ident ica l sheets of paper. Cr umple one into a ba l l . Watch what happens when you d rop them. The cr umpled paper fa l ls faster. So, we ma ke a new hy pothesis: "The shape of an object a f fects the speed of its fa l l ." 3.4. Experiment We desig n va r ious ex per iments to test whether a hy pothesis is tr ue. Experiment 1: objects in free fall Control the cond it ions: avoid d raughts that cou ld a f fect the fa l l of the objects. 1. Measu re the mass of the objects using sca les. 2 . Place the objects on a h igh hor izonta l su r face. 3. Ti lt the su r face so that they a l l fa l l at the same t ime. 4. Measu re the t ime they ta ke to fa l l . 5. Obser ve the resu lts: Keys Rubber Paper Mass 32 g 7 g 1.5 g Time 0.8 s 1.3 s 5.4 s Conclusion: it seems to be tr ue that heav ier objects fa l l faster. Experiment 2: objects with the same shape in free fall 1. Use an incl ined su r face so the objects ta ke longer to rol l dow n it . 2 . Place objects w ith d i f ferent masses inside ident ica l hol low ba l ls (A , B and C). 3. Li f t the str ip of wood at the sta r t . Measu re the t ime it ta kes the ba l ls to reach each point . 4. Wr ite dow n the resu lts for each ba l l . 4 4 Var iables a re the cha racter ist ics of a phenomenon that can have d i f ferent va lues. In physics and chemistr y, they a re usua l ly quantities such as temperature, mass or pressure. Conduct ing an ex per iment involves repeat ing an obser ved phenomenon under control led cond it ions to f ind out wh ich var iables a f fect it and how. A Steel B Sand C Paper Strip of wood 15
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