Intro physics course is beginning to move into 2d kinematics, stuck on the first real question.
a stone is thrown horizontally at 15m/s from the top of a cliff 44m high. what is the velocity of the rock after 2 seconds?
i tried 3(-9.8m/s2) and some other formula's but could never arrive at the correct answer of 24.7m/s. could someone explain how to arrive at this answer and the reasoning behind it?

A23 kg log of wood begins from rest, 300 m up a sluice (a water track used to transport logs, think of it as an inclined plane with negligible friction) inclined at 20° to the horizontal. after it reaches the flat waterway at the bottom it collides elastically with a 100 kg block of wood initially at rest near the base of the incline. (a) how long does it take the 23 kg log to travel down the incline? (b) what is the speed of the 23 kg log at the bottom of the incline? (c) what are the velocities of both blocks of wood after the collision? (d) what is the total kinetic energy before the collision? (e) what is the kinetic energy of the 23 kg log after the collision? (f) what is the kinetic energy of the 100 kg block of wood after the collision? (g) what is the total kinetic energy after the collision? (h) compare the total initial and total final kinetic energies. is this consistent with what you would expect for elastic collisions? explain!

Aknife blade is a(n) a. lever b. screw c. wedge d. inclined plane

Phase changes are chemical changes. true or false