A pendulum consists of a ball of mass 3.0 kg on a string of length 4.0 m. The ball is pulled back untilits center has risen to a height of 0.80 m. The ball is released such that it strikes a 1.0 kg block at thebottom of its swing. The block comes to a rest after traveling 2.0 m across a surface withμk= 0.15.What is the speed of the ball right after the collision? Is the collision elastic?

A 10-cm-long thin glass rod uniformly charged to 10.0 nC and a 10-cm-long thin plastic rod uniformly charged to - 10.0 nC are placed side by side, 3.90 cm apart. What are the electric field strengths E1to E3 at distances 1.0 cm, 2.0 cm, and 3.0 cm from the glass rod along the line connecting the midpoints of the two rods?

You are an astronaut in the space shuttle pursuing a satellite in need of repair. You are in a circular orbit of the same radius as the satellite (420 km above the Earth), but 24 km behind it.

(a) How long will it take to overtake the satellite if you reduce your orbital radius by 1.0 km?

___________ hr

(b) By how much must you reduce your orbital radius to catch up in 7.0 hours?
___________ m

Other things held constant, which of the following will affect the current ratio, assuming an initial current ratio greater than 1.0?

A flat square sheet of thin aluminum foil, 30 cm on a side, carries a uniformly distributed 285 nC charge.

Part A What, approximately, is the electric field 1.0 cm above the center of the sheet? Express your answer using two significant figures.

What, approximately, is the electric field 20 mm above the center of the sheet? Express your answer using two significant figures.

1. Consider the following data for a particular sample period when returns were high:

                                           Portfolio P                 Market Portfolio

Average Return               32%                            28%

Beta                                   1.3                              1.0        

Standard Deviation        40%                            30%

Calculate Jensen’s Alpha, the Sharpe ratio and Treynor’s ratio for both portfolio P and the Market. The T-bill rate during this period was 5%. By which measures did portfolio P outperform the market?

Dinitrogen pentoxide (N2O5) decomposes in chloroform as a solvent to yield NO2 and O2. The decomposition is first order with a rate constant at 45 ∘C of 1.0×10−5s−1.

Calculate the partial pressure of O2 produced from 1.47 L of 0.605 M N2O5 solution at 45 ∘C over a period of 18.5 h if the gas is collected in a 11.4-L container. (Assume that the products do not dissolve in chloroform.)

An engineer designed a valve that will regulate water pressure on an automobile engine. The engineer designed the valve such that it would produce a mean pressure of 4.2 pounds/square inch. It is believed that the valve performs above the specifications. The valve was tested on 170 engines and the mean pressure was 4.4 pounds/square inch. Assume the standard deviation is known to be 1.0. A level of significance of 0.02 will be used. Determine the decision rule.

Enter the decision rule

12. Calculate the pH of a buffer solution made from 0.30 M hydrofluoric acid and 0.70 M sodium fluoride after the addition of 0.08 mol of NaOH to 1.0 L of this solution.  Assume no change in volume.  The Ka for HF is 3.5 • 10-4.

Can someone guide me through this question? The answer is below but I can figure out how they got this answer.

Answer: pH = 4.01