Need hel plz 60 POINTS
4. A waiter carries a tray of food across a room. How much work was done on the tray?How do you know?

5. What is the equation for total mechanical energy?

6. Which of the following objects has more kinetic energy?

Explain your answer!!!
A 15 kg ball rolling north at 15 m/s

OR

A 15 kg ball rolling backwards at 7 m/s

At very high pressures, gases become and will eventually a) more dense; become hotter b) more dense; change to a liquid or solid c) less dense; combust d) less dense; turn into a liquid

In a classical model of the hydrogen atom, the electron moves around the proton in a circular orbit of radius 0.053 nm. what is the electron's orbital frequency? what is the effective current of the electron?

It may seem strange that the selected velocity does not depend on either the mass or the charge of the particle. (for example, would the velocity of a neutral particle be selected by passage through this device? ) the explanation of this is that the mass and the charge control the resolution of the device--particles with the wrong velocity will be accelerated away from the straight line and will not pass through the exit slit. if the acceleration depends strongly on the velocity, then particles with just slightly wrong velocities will feel a substantial transverse acceleration and will not exit the selector. because the acc