How does an increase in thermal energy affect the state of matter?

When thermal energy is added to a substance, its temperature increases, which can change its state from solid to liquid (melting), liquid to gas (vaporization), or solid to gas (sublimation). ... When the pressure exerted on a substance increases, it can cause the substance to condense.

Explanation:

Hope it will help use

one person pulls 90n one way and the other has 100n pulling the other way.

so the net force = 90 - 100 = -10n,

or the ans can be 10n if the picture shows -90n and 100n instead.