GGR270H1 Lecture : variables and data, scales of measurement

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purplezebra711

5 Oct 2011

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Variables and data: a variable is a characteristic of a population that changes or varies over time; its something that can be measured over time, ex. Male or female, plant species, etc: data: results from measuring variables [use data as the plural, multivariate, bivariate and univariate. Classifies observations into mutually exclusive [an element can only go into one box or another; only one category] and collectively exhaustive groups. A nominal variable is simply the name or category of the variable [ex. Its either male or female: ordinal: allows data to be ordered and ranked. People living in large towns, medium towns or small towns and could then group them by the top 12 cities for example: interval: unit distance separating numbers is important. Temperature [f or c] or taxable income [$] in this case, negative numbers can mean something: ratio: ratios of distance on a number scale.

Related Questions

The weight of an object is an example of_______

(a) a discrete random variable

(b) either a discrete or continuous random variable, depending on the weight of the object

(d) either a discrete or continuous random variable, depending on the units of measurement

greysquirrel645

In the following questions, assume that all variable expressed inquantitative error format are uncorrelated measurements.

1-Calculate W=x+y, and express answer in standard format.

x = 13.1 +/- 0.8 cm

y = 12.0 +/- 0.5 cm

2-Calculate W=x-y, and express answer in standard format.

x = (3.0 +/- 0.2) x 10^-4 kg m/s

y = (1.5 +/- 0.6) x 10^-6 kg m/s

The kinetic energy

of an object of mass

moving at a speed

is defined as $K=(1/2)mv^2$ . It seems reasonable to say that the speed of an object--and, therefore, its kinetic energy--can be changed by performing work on the object. In this problem, we will explore the mathematical relationship between the work done on an object and the change in the kinetic energy of that object.

Let us now consider the situation quantitatively. Let the mass of the sled be and the magnitude of the net force acting on the sled be. The sled starts from rest.

Consider an interval of time during which the sled covers a distance

and the speed of the sled increases from

. We will use this information to find the relationship between the work done by the net force (otherwise known as the network) and the change in the kinetic energy of the sled.

Find the net force

acting on the sled.

Express your answer in terms of someor all of the variables

, and

Find the net work

done on the sled.

Express your answer in terms of someor all of the variables

is defined as $K=(1/2)mv^2$ . It seems reasonable to say that the speed of anobject--and, therefore, its kinetic energy--can be changed byperforming work on the object. In this problem, we willexplore the mathematical relationship between the work done on anobject and the change in the kinetic energy of that object.

Let us now consider the situationquantitatively. Let the mass of the sled be and the magnitude of the net force acting on the sled be. The sled starts from rest.

Consider an interval of time duringwhich the sled covers a distance

and the speed of the sled increases from