A(n) 930 N crate is being pushed across a level floor by a force of 400 N at an angle of 20◦ above the horizontal. The coefficient of kinetic friction between the crate and the floor is 0.20. The acceleration of gravity is 9.81 m/s 2 . What is the magnitude of the acceleration of the box? Answer in units of m/s 2

Which statement is true if the refractive index of medium a is greater than that of medium b? a. total internal reflection is possible when light travels from air to medium b to medium a. b. total internal reflection is possible when light travels from medium a to medium b. c. total internal reflection is possible when light travels from medium b to medium a. d. total internal reflection is possible when light travels from air to medium a. e. total internal reflection is possible when light travels from air to medium b.

The amount of work done is determined by 2 factors. describe an example of work (using the scientific definition) list the 2 factors that determine the amount of work done.

Which best term to describe a chemical reaction that absorbs energy from its surroundings? a.thermal conductor b.thermal insulator c.endothermic d.exothermic