A spring scale in a French market is calibrated to show the mass of vegetables in grams and kilograms. (a) If the marks on the scale are $1.0 \mathrm{mm}$ apart for every $25 \mathrm{g}$, what maximum extension of the spring is required to measure up to $5.0 \mathrm{kg} ?$ (b) What is the spring constant of the spring? [Hint: Remember that the scale really measures force.