Weeks 2 Graded Assignment Question 3

[Nithin Babu]

Can support team clarify on:

1. whether the angle theta is assumed to be angle of declination or angle of inclination. In other words, is theta measured with respect to positive x-direction or negative x-direction. (Mathematically it is inclination but logically its the opposite!!!)
2. Does the bullet continue its trajectory if it hits a worker or does it stop?
3. Does hitting a worker on his feet (at y=0) count as unsafe for the worker?

I am writing this query as I think the questions can sometimes be tricky. I know it is a graded assignment and have taken care not to reveal anything other than necessary. If required I will delete this query after it gets answered.

Thanks in advance.

[subhajit POD]

Hi Nithin, 

Yes the inclination of a straight line is the angle it makes with positive X axis and logically it also makes sense. 

When you are finding the trajectory of the bullet you should get the equation of some straight line. It may or may not intersect with the line segment denoting the worker depending on their position. 

Hope it helps. I should not give you more hints than this regarding the graded assignments. 

Best

Subhajit 

[Malabika Guha Mustafi]

As per my understanding-

Theta is the angle of inclination ( angle between a line and x axis ) of a line. Theta is measured anticlockwise and right side of x axis. alpha is (180 degree- theta) , the adjacent angle of theta.  

tan alpha= - tan theta.

so, when a line makes an angle theta  with horizontal , for positive slope line , the slope is tan theta but for negative slope it is  tan alpha or  -tan theta .

Team please clarify.

On Sunday, 18 October 2020 at 22:23:25 UTC+5:30 Nithin Babu wrote:

So I should consider m=2/3 and not -2/3. I will delete this as soon as you answer this mail

[Nithin Babu]

Thanks for the clarification

[Malabika Guha Mustafi]

Welcome. But wait for team reply.

[Malabika Guha Mustafi]

Team please  response .

[subhajit POD]

Hi all, Yes Malabika you are right, the angle of inlcination of a st. line is measured as the angle the st. line making with positive X axis and in anticlockwise. 

So, when the angle of inclination is theta then the slope of the st. line is tan(theta). Now if this theta is an obtuse angle then tan(theta) is negative, which gives us the negative slope. 

It is important to remember the identity: 

tan(180- alpha)=-tan (alpha) 

Suppose your theta (the angle of inclination is 150 degree) then tan (150)= - tan (180-150)= - tan 30 , so it will be a st. line with negative slope. 

Hope it clears the doubt. 
Best

Subhajit

[Malabika Guha Mustafi]

Thank you

[LS Bhati]

Hi
Still it is not clear whether the bullet touching a worker where y=0 will kill him or not. This will help to answer the question. Please guide. 

Regards

On Sunday, 18 October 2020 at 22:12:14 UTC+5:30 subh...@onlinedegree.iitm.ac.in wrote:

[Rhea Jain]

Hi All,

I also have a similar doubt whether hitting a bullet on a worker's feet i.e. y=0 will kill him or not. 

Also, if the bullet hits a worker, would the bullet trajectory stop or will it continue making others standing behind him unsafe?

Please reply as these doubts are making the answer uncertain.

Rhea

[Malabika Guha Mustafi]

https://groups.google.com/a/nptel.iitm.ac.in/g/ma1001-discuss/c/98zWtlJm0DQ/m/IUvSPkpEAwAJ

[Rhea Jain]

thank you

[Nithin Babu]

Sir, you are contradicting yourself now. Can you please give an explanation to this.