A student performs an experiment to see how catalysts affect the rate of a reaction. He notices that when the reaction is nearly finished, it stops bubbling. He wants to know how much faster the reaction occurs when a catalyst is used. Which is the best method for him to measure his data? Use a stopwatch to record the time it takes for the bubbling to stop. Estimate the time of the reaction by counting aloud. Count the number of bubbles formed by the reaction. Measure the size of the bubbles produced with a ruler.

Ablock of mass m = 2.5 kg is attached to a spring with spring constant k = 790 n/m. it is initially at rest on an inclined plane that is at an angle of 28 degrees with respect to the horizontal, and the coefficient of kinetic friction between the block and the plane is k = 0.14. in the initial position, where the spring is compressed by a distance of a = 0.18 m, the mass is at its lowest position and the spring is compressed the maximum amount. take the initial gravitational energy of the block as zero. b) if the spring pushes the block up the incline, what distance, l, in meters will the block travel before coming to rest? the spring remains attached to both the block and the fixed wall throughout its motion.

The radius of a sphere is increasing at a rate of 9 cm/ sec. find the radius of the sphere when the volume and the radius of the sphere are increasing at the same numerical rate.

How does the electric potential energy between two charged particles change if one particle is reduced by a factor of 3? a. increased by a factor of 3 b. it is decreased by a factor of 9 c. it is reduced by a factor of 3 d. it is increased by a factor of 9