Answer:
<em>The angle introduces an error on the mesure of the weight</em>
Explanation:
<u><em>Weight and Normal Forces</em></u>
When an object is resting on a horizontal surface, its weight is directed downwards and the normal force has the same magnitude and opposite direction, i.e. directed upwards. When some angle α exists between the surface and the horizontal plane, the scale keeps 'feeling' the Normal force, but it's not equal to the weight anymore, but to the perpendicular component of the weight to the surface where the scale is placed. It can be found that the component of the weight is m.g.cosα
If, for example , the real measure is
That is, 98.5% of the correct weight. So it's important to measure weight on horizontal surfaces