In an open system such as a campfire, matter can lose particles, gain particles or exchange particles.
When the object is big enough to contract itself into a ball.
Answer:
a. It always points perpendicular to the contact surface.
Explanation:
"Normal" means perpendicular. Normal forces are always perpendicular to the contact surface.
B.temperature is an indirect measurement of the heat energy in a substance
I think wavelength is the correct answer. Correct me if Im wrong. Hope this helps!
