Learn Hardcore Swahili: Uzito ukiongezeka, weka maembe machache zaidi kwenye mizani nyingine. - If the weight increases, put a few more mangoes on the other scale.

u- = subject prefix agreeing with uzito (“weight”), a U-/class 14 noun
-ki- = “when/if (and then)” marker
ongezeka = “to increase” (intransitive) So u-ki-ongezeka = “if/when it increases.”

Why is the subject prefix u- used (not a- or i-)?

Because uzito is a U-/class 14 noun. Class 14 subjects take the prefix u- in the verb. Example: “Uzito unaongezeka” = “The weight is increasing.”

Can I use kama or ikiwa instead of the -ki- form?

Yes:

Kama uzito unaongezeka, … = If the weight is increasing, …
Ikiwa uzito utaongezeka, … = If the weight will increase, … The -ki- form is compact and idiomatic for “when/if (and then).” Kama is very common in speech; ikiwa is a bit more formal/explicit.

What about unapoongezeka and utakapoongezeka?

They’re “when” forms with different time nuances:

Uzito unapoongezeka, … = When(ever)/as the weight increases (habitual/general).
Uzito utakapoongezeka, … = When the weight increases (at some future time). Your sentence uses -ki- for a direct “if/when → then” sequence.

Is weka an imperative? How do I address more than one person politely?

Yes, weka is the 2nd person singular imperative “put.” For plural, use wekeni. To be polite, add tafadhali:

Singular: Tafadhali weka …
Plural: Tafadhali wekeni …

Could I say ongeza instead of weka?

Yes, if the idea is “add” rather than just “put.” For example:

Ongeza maembe machache zaidi kwenye mizani nyingine. Ongeza (transitive) = add/increase something. Ongezeka (intransitive) = increase (by itself).

What’s the singular of maembe, and which noun class is it?

Singular: embe (class 5), plural: maembe (class 6). Adjectives/quantifiers must agree with class 6, hence ma-chache (few).

Why is it maembe machache zaidi and not just maembe chache?

machache agrees with class 6 (maembe). Plain chache would not agree.
zaidi means “more,” so machache zaidi = “a few more.”

Where does zaidi go? Can I say “zaidi maembe” or “zaidi machache”?

Put zaidi after the word/phrase it modifies:

maembe zaidi = more mangoes
machache zaidi = a few more “Zaidi maembe/machache” is not natural. For “more than,” use zaidi ya
- number: zaidi ya tatu = more than three.

Could I say maembe mengine machache instead? Is there a nuance?

maembe machache zaidi = a few more mangoes (additional quantity).
maembe mengine machache = a few other mangoes (different ones, not the same ones). Both are grammatical; choose based on whether you mean “additional” vs. “different/other” items.

What does mizani nyingine mean exactly—“another scale” or “the other scale”?

It can mean either. Context decides:

kwenye mizani nyingine = on another/other scale To make it definite, add a demonstrative: kwenye ile mizani nyingine = on that other scale. To emphasize “another one,” you can say kwenye mizani nyingine moja.

Why is it nyingine (not mingine), even though “mizani” starts with “mi-”?

Because mizani belongs to the N-class (9/10), whose “other” form is nyingine (same for singular and plural). The initial “mi-” in this loanword doesn’t make it class 4; agreement with nyingine shows it’s N-class.

Is mizani singular or plural? How do I tell?

In the N-class, singular and plural often look the same. mizani can be singular or plural; agreement and context disambiguate:

Singular: mizani nyingine (another scale)
Plural: mizani nyingine (other scales) Numbers help: mizani mbili = two scales.

Why use kwenye here? Could I use juu ya or katika?

kwenye = at/on/in (general locative; very common): “on the scale.”
juu ya = on top of (more literal surface contact).
katika = in/inside (container-like sense). All are possible; here kwenye or juu ya fit best; katika would sound odd for a flat scale.

Can I put the condition second: “Weka …, uzito ukiongezeka”?

You can, and it’s understood, but Swahili usually puts the -ki- clause first for a clear “when/if → then” flow. Your original order is more natural.

How do I say the opposite: “If the weight decreases …”?

Use -ki- with the appropriate verb:

Uzito ukipungua, … = If/when the weight decreases, …
Synonyms: ukishuka, ukipungua uzito, etc. For a negative condition: Uzito usipoongezeka, … = If the weight doesn’t increase, …

Is there any difference between ongezeka and zidi?

ongezeka = increase (grow in amount) by itself.
zidi = exceed/go beyond; as a verb it can also mean “increase further.” So you might hear Uzito ukizidi, … (if the weight keeps increasing/if it exceeds). Use ongezeka for neutral “increase,” zidi when implying “too much/exceeding” or “further.”