Two balls of different masses are dropped from a building, and they hit the ground at the same time. How does the force of gravity, exerted on each ball, depend on its mass?
A
It is independent of the ball’s mass.
B
It is directly proportional to the ball’s mass.
C
It is inversely proportional to the ball’s mass.
D
It is directly proportional to the ball’s mass squared.

Why is rain likely when warm, moisture-laden air meets cold air? a) the lighter warm air will rise and cool down, causing condensation and rain. b) the cold air moves faster and pushes the warm air away, causing condensation and rain. c) the moisture in the warm air condenses on contact with the cold air, causing rain to fall. d) the cold air mixes with the warm air, reducing its temperature causing moisture to condense.

Athin electrical heater is inserted between a long circular rod and a concentric tube with inner and outer radii of 20 and 40 mm. the rod (a) has a thermal conductivity of ka = 0.15 w/(m*k), while the tube (b) has a thermal conductivity of kb = 0.8 w/(m*k) and its outer surface is subjected to convection with a fluid of temperature t= -15°c and heat transfer coefficient 60 w/(m2 *k). the thermal contact resistance between the cylinder surfaces and the heater is negligible. (a) determine the electrical power per unit length of the cylinders (w/m) that is required to maintain the outer surface of cylinder b at 15°c. (b) what is the temperature at the center of cylinder a?

Auniform electric field exists in the region between two oppositely charged plane parallel plates separated by a distance of 1.60 cm . a proton is released from rest at the surface of the positively charged plate and strikes the surface of the opposite plate in a time interval of 3.20×10-6 s. 1-find the magnitude of the electric field. use 1.60×10-19c for the magnitude of the charge on an electron and 1.67×10-27kg for the mass of a proton 2-find the speed of the proton when it strikes the negatively charged plate