4. The correct unit for a joule is a) 1kg-m/s b) 1kg-m^2/s^2 c) 1g-cm/s d) 1kg-cm^2/s^2

The correct answer is b) $1kg-m^{2}/s^{2}$.<br /><br />A joule is the SI unit of energy, work, and heat. It is defined as the amount of work done when a force of one newton is applied over a distance of one meter. The unit of force is the newton, which is defined as one kilogram-meter per second squared (1 kg·m/s²). Therefore, the correct unit for a joule is 1 kilogram-meter squared per second squared (1 kg·m²/s²).