Tackling the Difficult Death Problem in Physics Honors Class

In summary, the conversation is about a recent test in a physics honors class that had a difficult "death problem" worth 20 points. The problem involved a cannon firing a projectile down a hill with a specific angle and speed. Many people struggled with the problem and some were unable to solve it. The conversation ends with the person claiming to have solved the problem and getting a distance of 1440 meters, while the expert believes the correct answer is 1486 meters.
  • #1
liljediboi
28
0
hey. i am in a physics honors class, and we just had a test.

each test has 9 questions, 8 which are decent, and the last one is the "death problem" this problem is worth 20 point, double of the others (if you did the math, if you get die on the death problem, the highest score possible is 80).

anyways. the last death problem is as follows

a cannon fires a projectile (no air or wind) at 100 m/s at a 20 degrees angle north of west. it is fired down a "hill" (which is impossibly straight) the hill has a 20 degree angle north of east. find d (see picture.

talked to tons of people, nobody knows if they got it, and many did not even have time to do it. looks like a huge curve coming.

and the obvious question. WHAT IS THE ANSWER?? and please show work for full credit. haha
 

Attachments

  • deathproblem.jpg
    deathproblem.jpg
    8.6 KB · Views: 383
Last edited:
Physics news on Phys.org
  • #2
a cannon fires a projectile (no air or wind) at 100 m/s at a 20 degrees angle north of west. it is fired down a "hill" (which is impossibly straight) the hill has a 20 degree angle north of east. find d (see picture.

You do understand, don't you, that we CAN'T "see picture" because you didn't post it! I assume that "d" is the distance from the point at which the projectile is fired to where it hits the ground. The real point of the problem is to find where it hit.

You say "at 20 degrees angle north of west". That sounds like you mean it is aimed 20 degrees to the north of due west but if that is true, we don't know the upward angle at which the projectile is fired.

I'm going to take it that the cannon is aimed "north-west" (that is "45 degrees north of west", and that it is pointed 20 degrees above the horizontal. Also that the hill slopes downward in the same direction as the cannon is aimed (which makes the problem MUCH easier) with a 20 degree downward slope.

Here's how I would do the problem: We can ignore the direction. Since the cannon is fired in the same direction as the hill slopes, just do it as a standard two dimensional problem- take (0,0) as the position of the cannon and the x-axis in the direction the cannon is fired. First ignore the hill. Use the standard (parabolic) formula for a projectile launched at angle [theta] with initial speed v0:
x= v0 cos[theta] t, y= -(g/2) t2+ v0 sin[theta] t.
You can easily solve solve for t in terms of x and replace it in the formula for y to get y as a function of x. In a simple, "standard" problem, the projectile would hit where y= 0 so you would solve y= 0 for x.

Here, the ground slopes. Knowing that the ground slopes downward in the x direction, find the equation of the straight line:
it is y= (tan[theta])x where [theta] is the angle the line makes with the x-axis (in this problem it is -20 degrees).

The projectile "hits" the ground when it crosses that line.
Solve the two equations y= f(x) for the projectiles motion and
y= mx for the ground simultaneously to find the point at which the projectile hits the ground. Once you know the coordinates of that point, you can find d, the distance between (0,0) and that point.
 
  • #3
attachment is working now. it is not very accurate, as my friend has pointed out, but give me a break, i used mspaint.

anyways the cannon fires 100 m/s [W 20 N]
 
  • #4
Then you have not given us the angle "of elevation" of the cannon barrel and it is impossible to answer this.
 
  • #5
whatever. found out how to do it, insanely easy, its 1440 m
 
  • #6
"whatever".

Ah, the enthusiasm!

I glad it was "insanely easy". You do understand, don't you that you never posed a solvable problem here?

Assuming that the problem was as I interpreted it, 1440 m is close.
I get 1486 meters.
 

1. What is the "Difficult Death Problem" in Physics Honors Class?

The "Difficult Death Problem" refers to a hypothetical scenario in which a person is standing on the edge of a cliff and has a 50% chance of dying if they jump off. This problem is often used in physics courses to explore concepts such as probability, energy, and forces.

2. How is this problem relevant to physics?

The "Difficult Death Problem" allows students to apply their knowledge of physics concepts to a real-life scenario. By analyzing the forces and energy involved in the situation, students can understand the potential consequences of their actions and make informed decisions.

3. What makes this problem difficult?

The difficulty of this problem lies in its moral and ethical implications. Students must grapple with the idea of taking a risk with a 50% chance of death, even though it may lead to a positive outcome. This challenge encourages critical thinking and decision-making skills.

4. How can students approach this problem?

There is no one right answer to this problem, as it is meant to stimulate discussion and critical thinking. Students can analyze the forces and energy involved, consider the potential consequences, and discuss the moral and ethical implications of different choices.

5. What are some key takeaways from tackling this problem?

By tackling the "Difficult Death Problem," students can gain a deeper understanding of physics concepts such as probability, energy, and forces. They can also develop critical thinking, decision-making, and ethical reasoning skills. This problem serves as a valuable tool for applying theoretical knowledge to real-life situations and fostering meaningful discussions about morality and ethics.

Similar threads

Replies
9
Views
1K
  • Introductory Physics Homework Help
Replies
3
Views
2K
  • STEM Career Guidance
Replies
1
Views
1K
Replies
2
Views
853
  • Introductory Physics Homework Help
Replies
14
Views
2K
  • STEM Academic Advising
Replies
2
Views
985
  • STEM Educators and Teaching
Replies
3
Views
1K
  • Introductory Physics Homework Help
Replies
6
Views
920
  • Introductory Physics Homework Help
Replies
4
Views
2K
Replies
2
Views
5K
Back
Top