Phil leans over the edge of a cliff and throws a rock upward at 5 m/s. neglecting air resistance, two seconds later the rock's speed is a. 15 m/s. b. 5 m/s. c. 10 m/s. d. zero. e. none of the above

A. 15m/s

Explanation:

Since air resistant is neglected, gravity is the only force affecting the rock. Suppose the constant gravitational acceleration g = -10 m/s2, negative because it's in the opposite direction (downward) to the upward velocity. We can calculate the velocity of the rock after 2 seconds using the following equation of motion:

where v0 = 5 m/s is the initial velocity, t = 2 seconds

So the rock speed after 2 seconds is 15 m/s

are there options? cause you ain’t. real specific