A golf ball with a mass of 46g is hit from the ground with a speed of 20m/s. It takes that ball 1 second to reach its highest point. For all parts assume that the air resistance is negligible. The system includes the golf stick, golf ball, and Earth. I created an energy bar chart attached below. The part where I'm getting stuck is figuring out what is doing the negative work. At first I thought it was the Earth but it can't be because it is part of the system. Then I started doubting my energy bar chart. The final Ug would be mgh so I did m=0.046(covert from g to kg), g=-10, and h=5(figured out using kinematics). The Ug would then be -2.3. But wouldn't it have to be positive 2.3 for energy to be conserved? But at the same time, how can it be positive; g is always negative? So please clear up this problem, I've been stressing on it too much.

If you were on a jury, do you think you would expect individual characteristics in the evidence? why or why not? what effects might it have if individuals expect to have individuals characteristics presented? this question is for forensic science

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!

Achlorine atom has 17 protons and 18 neutrons. what is its mass number? what is its atomic number?