Abicycle wheel rotates uniformly through 2.0 revolutions in 4.0 s. what is the frequency of the wheel's rotation?

The frequency is defined as the number of cycles done in one second:

where N is the number of cycles and t is the time taken to complete N cycles. The wheel in this problem does N=2 revolutions in a time of t=4.0s, therefore its frequency of rotation is: 

This is what i found on google “according to the collision theory, the following criteria must be met in order for a chemical reaction to occur: molecules must collide with sufficient energy, known as the activation energy, so that chemical bonds can break. molecules must collide with the proper orientation.” i hope this information you.