a ladder at rest is leaning against a wall at an angle. which of the following forces must have the same magnitude as the frictional force exerted on the ladder by the floor? justify your answer. (a) the force of gravity on the ladder (b) the normal force exerted on the ladder by the floor (c) the frictional force exerted on the ladder by the wall d) the normal force exerted on the ladder by the wall

An architect plans to use solar energy to heat the next house he designs. what principle of absorption and infrared energy can be applied to the design of the new house? how could she apply to those principals?

Which best describes the first law of thermodynamics as compared to the second law of thermodynamics? a. the first law describes how thermal energy is conserved but not the direction it moves. b. the first law describes the direction thermal energy moves but not how it is conserved. c. the first law describes how thermal energy can be created but not how it can be destroyed. d. the first law describes how thermal energy can be destroyed but not how it can be created.

Atoms seldom exist as independent particles in nature a) as single particles, most atoms have low potential energy b) their electronegativity is much lower when they combine with other atoms c) atoms are more stable when they combine with other atoms d) neutral particles are rare