strong
彊 centers on strength and forcefulness. Its single given meaning, "strong," captures the core idea of physical or metaphorical power.
彊 combines 弓 (bow) with 畺, which likely contributes the sound and reinforces the idea of strength or tension. The exact historical development of 畺 is uncertain, but the character is associated with powerful, taut bows.
A bow (弓) that is tightly drawn and reinforced by the strong-looking 畺 component: 彊 represents strength and tension.
For キョウ, imagine a strong bow that makes a loud "kyow!" sound when released: kyow -> キョウ, and the bow's power shows its strength.
strenuous effort