According to the collision theory, all collisions do not lead to reaction. which choice gives both reasons why not all collisions between reactant molecules lead to reaction? 1. the total energy of two colliding molecules is less than some minimum amount of energy. 2. molecules cannot react with each other unless a catalyst is present. 3. molecules that are improperly oriented during collision will not react. 4. solids cannot react with gases. a. 1 and 3 b. 3 and 4 c. 2 and 3 d. 1 and 2 e. 1 and 4

The desk has a weight of 75 lb and a center of gravity at g. determine the initial acceleration of a desk when the man applies enough force f to overcome the static friction at a and b. also, find the vertical reactions on each of the two legs at a and at b. the coefficients of static and kinetic friction at a and b are ms = 0.5 and mk = 0.2, respectively

Which statement is best supported by the information in the chart? wave y is moving the fastest. wave x is moving the fastest. all of the waves are moving at the same speed. all of the waves have the same value of wavelengths per second.

Which of the following correctly describes what happens when an atomic bomb explodes? small pieces of fissionable material are joined and form a body with a mass greater than the critical mass, the relative number of neutrons escaping decreases, and a chain reaction and explosion result. large pieces of fissionable matter are brought together quickly and form a body with a mass smaller than the critical mass, the relative number of escaping neutrons increases, and a chain reaction and explosion result.