ic_090916_qa

course 201

9/21 1 am

Question: `q001. Note that there are 14 questions in this assignment.

If an object moves 12 meters in 4 seconds, then at what average rate is the object moving? Explain how you obtained your

result in terms of commonsense images.

YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY

Your solution: 12 meters/4 seconds= 3 meters/second

This means that they system covers three meters every second that passes, and in four seconds it would have traveled 12

meters

confidence rating:5

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

.............................................

Given Solution:

Moving 12 meters in 4 seconds, we move an average of 3 meters every second.

We can imagine dividing up the 12 meters into four equal parts, one for each second. Each part will span 3 meters,

corresponding to the distance moved in 1 second, on the average.

&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&

Self-critique (if necessary):

------------------------------------------------

Self-critique rating:5

*********************************************

Question: `q002. How is the preceding problem related to the concept of a rate?

YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY

Your solution: The preceding problem was simply a division of the change in position by the change in clock time, or

`ds/`dt, which we know as the average rate of velocity. All rates are calculated this way, by dividing the change in one

variable by the change in another.

confidence rating: 5

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

.............................................

Given Solution:

A rate is obtained by dividing the change in a quantity by the change in another quantity on which is dependent. In this

case we divided the change in position by the time during which that change occurred.

More specifically

• The rate of change of A with respect to B is defined to be the quantity (change in A) / (change in B).

An object which moves 12 meters in 3 seconds changes its position by 12 meter during a change in clock time of 3 seconds. So

the question implies

• Change in position = 12 meters

• Change in clock time = 3 seconds

When we divide the 12 meters by the 3 seconds we are therefore dividing (change in position) by (change in clock time). In

terms of the definition of rate of change:

• the change in position is the change in A, so position is the A quantity.

• the change in clock time is the change in B, so clock time is the B quantity.

So

(12 meters) / (3 seconds) is

(change in position) / (change in clock time) which is the same as

average rate of change of position with respect to clock time.

Thus

• average velocity is average rate of change of position with respect to clock time.

&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&

Self-critique (if necessary):

------------------------------------------------

Self-critique rating:5

*********************************************

Question: `q003. Is object position dependent on time or is time dependent on object position?

YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY

Your solution: Object position is dependent on time. I came to this conclusion because when we graph the two, time is

always expressed as the x variable, and x is always the independent variable. Change in y is always dependent on x, and y is

represented by object position in this case. Reasoning further, time will always be independent, as it runs on its own in all

instances, dependent upon absolutely nothing.

confidence rating:5

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

.............................................

Given Solution:

Object position is dependent on time--the clock runs whether the object is moving or not so time is independent of position.

Clock time is pretty much independent of anything else (this might not be so at the most fundamental level, but for the

moment, unless you have good reason to do otherwise, this should be your convention).

&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&

Self-critique (if necessary):

------------------------------------------------

Self-critique rating:5

*********************************************

Question: `q004. So the rate here is the average rate at which position is changing with respect to clock time. Explain

what concepts, if any, you missed in your explanations.

YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY

Your solution: I am not aware of any concepts that I overlooked

confidence rating:5

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

.............................................

Given Solution:

Be sure you have reviewed all the definitions and concepts associated with velocity. If there’s anything you don’t

understand, be sure to address it in your self-critique.

"

&#This looks very good. Let me know if you have any questions. &#