The moon appears half lit, half dark from the surface of Earth on two days each month. What causes this? (1 point) Half of the moon's surface that is illuminated by the sun is visible from Earth's perspective.

Earth’s shadow is blocking the light from the sun.

Half of the moon is totally eclipsed.

It is a partial lunar eclipse.

Oxygen and nutrients are moved through the body by the: a. circulatory system c. lymphatic system b. digestive system d. reproductive system

Calculate the mass of an object that has a momentum of 100kg x m/sec and velocity of 4 m/sec

Air is contained in a variable-load piston-cylinder device equipped with a paddle wheel. initially, air is at 400 kpa and 17°c. the paddle wheel is now turned by an external electric motor until 75 kj/kg of work has been transferred to air. during this process, heat is transferred to maintain a constant air temperature while allowing the gas volume to triple. calculate the required amount of heat transfer in kj/kg.