ANSWER BOTH QUESTIONS (a)
The absorbance of mixture at 400 nm was 0.40. Using
the standard curve, calculate the concentration of
haemoglobin in g/dl for this female patient.
(b) Comment on the concentration of haemoglobin of the
patient. The normal range of haemoglobin in female
adult varies from 12.0-15.8 g/dl.

Elias is almost correct. he just got it backwards.the correct answer is that it demonstrates elastic potential energy transforming into kinetic energy.

Because a model would make the investigation easier to understand

U whay do you need with?

Mass is the amount of matter in an object.  weight is the measurement of the pull of gravity on an object.  say for example, you travel to the moon which has a different gravitational field compared to the gravitational field of earth. (gravitational fields: earth = 1, moon = 0.165)  now when you are on the moon, the pull of gravity on you is different than on the earth. and as weight is the measurement of the pull of gravity on an object, that means yes, your weight can and will change on the moon.  however, on the moon, on earth or even on jupiter, the amount of mass inside of you remains the same. meaning your physical mass remains constant.  in conclusion it is possible for your weight to change as your mass remains constant.