Why did the Sages forbid riding animals on Shabbat?
The real concern: while riding, you might break a branch to use as a switch — which is a toldah of reaping (detaching from the ground). The shevut prevents this.
Question 2
Can you squeeze a lemon into food on Shabbat?
Squeezing for food improvement (directly onto food) is different from squeezing for juice extraction. Onto food = permitted. Into a cup for juice = depends on the fruit type.
Question 3
Why is taking medicine on Shabbat generally forbidden?
The decree exists because medicine preparation typically involves grinding (a melachah). To prevent grinding, the Sages forbade casual medicine-taking.
Question 4
Can you select good food from a mixture that contains both good and bad items on Shabbat?
Three conditions for permitted selecting: (1) by hand (no utensil), (2) removing good from bad (not bad from good), (3) for immediate use. Meet all three = permitted.
Question 5
You want to crush pepper for your Shabbat meal. How should you do it?
Doing it the normal way (mortar/pestle) is forbidden. Doing it abnormally (knife handle on a bowl) is permitted — the unusual method signals it's not regular weekday grinding.