Estudio de la comunidad de micromamíferos como potenciales reservorios de

Conceptual part

1) List several repetitive phenomena that occur in nature and that could serve as reasonable weather patterns.

Sun - The time when the moon becomes full, the beginning of a season, solar cycles, the movement of the stars, etc..

2)

a. You can combine two vectors of different magnitude to give a zero resultant? Sun - No

b. They can do three vectors? Sun - If

3) List several scalar quantities.

Sun - mass, time, density, volume, temperature, electric current, etc.. 4) Is time a vector? Why?

Sun - No, that the management and direction of a vector has no restriction on its orientation. Practical part

1) Express your height in miles.In your answer using only prefixes. Sun - If you measure 1.67 meters then say you write 1.67 milli Kilo meters.

2) A plane travels 876.5 [km] in a straight line at an angle of 37.5to the North East.How much the plane has traveled both to the North and to the East, from its starting point?.Help:

Sun - Eastbound: 876.5 cos (52.5  = 533.6 [km] Northbound 876.5 sin (52.5  = 695.4 [km]

Since 90- 37.5= 52.5angle that is taken with respect to the horizontal.

3) Two trucks carrying sand.One of these, B, has a small hole in its base through which the sand is falling to the floor. They have taken the following mass versus time for both trucks:

Data # Time [min] A forklift Mass [kg] Cart B mass [kg]

1 0.0 8.75 _8.75 2 1.0 8.76 7.77 3 2.0 8.75 _6.74 4 3.0 8.77 5.76 5 4.0 8.75 _4.75 6 5.0 8.75 _3.76 7 6.0 8.74 _2.73 a) Plot:

 The mass versus time for the truck to

b) Because if A mass is constant we have different data?

Sun - Because when we take measurements random errors always exist, why not find a single result if not several.But note that the difference between them (mass of Cart A) is not great. These differences are known as natural statistical fluctuations.

4) The number of seconds in a year can be replaced conveniently by10.What is the percentage error of this figure?. Take = 3.141592653

Sun - 10 = 31415926.53

In a year of 365 days or 8760 hours are 31,536,000 seconds.Therefore the error percentage is 0.38%

Remember And

This is a rough estimate because in a year when there are actually 365.2 days.

June 8, 2003

REGIONAL PEACE

2nd of Secondary

SOLUTIONS

a. Ifa b = 0,does it follow thata andbare perpendicular to each other?

Sun - Yes, since by definition ab =(a) (b) cos  as cos  = 0 if and only if= 90thena andb are perpendicular.

b. Ifa = 0, Should be paralleltoandb?

Sun - Yes, since by definitiona =(a) (b)sin u and as sin  = 0 if and only if= 0 thenaandbare parallel.

c. Can a dot product between vectors be a negative amount?

Sun - Yes, you can.Which can not be negative is the magnitude of a vector. 6) List several scalar and vector quantities.

Scalar: mass, time, density, volume, temperature, electric current, etc..

Vectors: Strength, Speed, Acceleration, Magnetic Fields, Electric, Gravity; Momentum, Torque,

7) What experimental evidence exists to assume that the speed of sound is the same for all wavelengths?

Sun - Any piece of music, which is a collection of different wavelengths of sound waves, could never be heard as we do if the speed was different for certain wavelengths, as certain notes come to us much later or earlier than the other, you think? Would hear at the wrong without understanding anything.

8) What is it that causes mirages? Do you have something to do with the fact that the refractive index of air is not constant but changes to its density?Draw rays explaining the phenomenon. Sun - They did have a lot to do.The refractive index is sensitive to temperature changes.The mirages usually happen in deserts or on paved roads in a region very hot places exceeding 40 C, so ground-level air is hot and have lower density than the cooler air rises creating a series of strata or layers of different temperature levels. A layer of cold air, another of hot air and cold another produce a lens which bends the light rays and makes an image appear which can not be.

Practical part

5) A cylindrical vessel containing water has a radius of 2 cm.In 2 hours the water level low 1 mm.Estimate in grams per second, the evaporation rate at which water is evaporating.

Sun - The volume of water that falls is [Cc s -1]. 1cc water = 1 g of water. 1 [mm] = 0.1 [cm].Therefore [G s -1]

6) The lowest tone that can detect the human ear as sound is about 20 [Hz] and the highest is about 20000 [Hz].What is the wavelength of each of them in the air?. The speed of sound in air is 331.3 [ms -1].Indicates a wavelength where the wavelength and amplitude.

Sol - As and [Ms -1] then the wavelengths are 16,565 [m] and 16,565 [mm]

7) What should be the height of a vertical mirror, so that a person 6 feet tall to be able to observe the entire image?. Assume that your eyes are 4 inches below the top is its head

Sun - The figure shows the trajectories of rays that leave the top of the head of the individual and his toes. These rays chosen so that enter the eye after reflection, affect the vertical mirror in points a and b respectively.The mirror needs to occupy only that region between these two points.Projecting rays reaching the eye towards the place where they form the mirror image is that this should have half the height of the individual, ie 3 feet. Note that this height is independent of the distance at which is the person in the mirror.

8) Has been taken following the motion of a body:

Data # Time [s] Position [m] Speed [ms -1] Acceleration [ms -

2] 1 0.0 1.0 4.0 -3.8 2 1.0 3.7 _1.8 -1.2 3 2.0 4.8 _0.7 -1.0 4 2.5 5.0 _0.0 -1.9 5 3.5 3.9 -3.0 -4.9 6 4.0 1.4 -6.2 -7.3 Plot:

 the position versus time

 the speed versus time

June 8, 2003

REGIONAL PEACE

3rd of Secondary

SOLUTIONS

Conceptual part

1) What is the difference between mass and weight? Much do you weigh?

Sun - The mass is a scalar, its units are [kg], the weight is a vector, is a force therefore is measured in Newtons [N].If you say you have a mass of 66 [kg] weights then 66 [kg] [ms -2] = 645.15 [N].

9775 [ms -2] is gravity in La Paz. 9.81 [ms -2] is the gravity at sea level.

1.67 [ms -2] is the gravity on the moon. How much would you weigh on the moon?

2) Everyone knows that when you look in a mirror is an inversion of the left and right.The right hand seems to be a left, left eye seems to be one law, etc..Is it possible to design a mirror system that would allow to observe an image as the way in which people normally observed?If possible, draw a picture with some typical ray showing that this is true.

Sun - If possible, be requires two mirrors that are joined at an angle of 90 between them. Each image in a mirror will be reflected in the other mirror as to achieve reverse what we usually see as a result finding the desired image.

Sol - A body wholly or partly immersed in a fluid is pushed upward by a force that equals the weight of the fluid displaced by said body (Archimedes).

The principle that expresses the conservation of mass in a fluid movement is known as the continuity equation:

Where is the fluid density,

is the area

through which the fluid at a given time and is the fluid