Saturday, July 24th, 2010

### Solution:

A number a in the domain of a given function f is called a critical number ‘(a) = 0 or f ‘ is undefined at x = a.

Relative extrema are the minimums or maximum points on a part of a curve, while absolute extrema are the minimums and maximum points along the entire curve.

Now we are looking at the following curve:

f (x) =

To find the extrema, we take the first derivative and figure out at what value of x, the first derivate of the function equals to zero:

f’(x) = 2x-6

f’(3) = 0

As you can see the function is decreasing from negative infinity to 3, and increasing from 3 to infinity. The critical number is 3. There is only one relative (or local) minimum at (3, -9).

Friday, July 23rd, 2010

### Solution:

In the physical sciences, the amount of a sample is often given in terms of moles (i.e. Avogadro’s number, or 6.02214179 x 10^{23}):

Friday, July 23rd, 2010

### Solution:

First, let’s define what a Newton (N) is: “The Newton (N) is defined as the amount of force that, when acting on a 1 kg mass, produces an acceleration of 1 m/s/s (one meter per second per second). Therefore, 1 N = 1 kg =D7 1 m/s/s.”

The force of friction opposing the 325 N force is .25 * 925 N (which is equal to 231.25 N). The force pulling the crate is 325 N * cos(25), i.e. 294.55 N. (This is the component of force acting parallel to the floor.)

Take the difference between these two and you will have the net force pulling the crate (which is 63.3 N). Using Newton’s equation F = ma, you will find the acceleration by dividing the net force by the mass of the crate (the mass is 925 =/(one standard gravity [9.80665 m/s/s], or 94.32 kg). The acceleration is therefore 63.3 N / 94.32 kg, which equals 0.671 m/s/s.

Saturday, July 17th, 2010

### Solution:

A good absorber of radiant energy, like a black surface, sends to get hot. If it is a poor emitter, that means it will remain hot for a long time. Therefore, an object that is both a good absorber of radiant energy and a poor emitter would tend to be hotter than its surroundings.

Friday, July 16th, 2010

### Solution:

Specific heat capacity for water = 4.18 Joules/(gram*degree Celcius)

(how much energy is required per gram per change in degrees C)

mass = 4g

Change in temperature = 6 deg C

energy required = mass * change in temperature * specific heat capacity

= 4g * 6 deg C * 4.18 J/(g*deg C)

= 100.32 Joules

Friday, July 16th, 2010

Vector quantities have two characteristics: magnitude and a direction. Scalar quantities only have magnitude.