Exposure to what type of radiant energy is sensed by human skin as warmth? a). infrared b). ultraviolet c). gamma rays d). x-rays

Ineed ! it’s science and it’s due tomorrow!

Naoki's bicycle has a mass of 10 kg. if naoki sits on her bicycle and starts pedaling with a force of 168 n, causing an acceleration of 2.8 m/s2, what is naoki's mass?

What is the solubility-product constant of barium sulfate, baso4, if a saturated solution is 1.03 ´ 10-5 m?