RELATIVE MOTION wooden boxcar, sniper, bullets oh my

AI Thread Summary
The discussion revolves around a physics problem involving relative motion, where a wooden boxcar moves on a track while a sniper fires a bullet at it. The bullet, initially traveling at a speed of 650 m/s, enters and exits the boxcar's walls directly opposite each other, indicating a specific angle of fire. The problem requires understanding the relationship between the bullet's speed, the boxcar's speed of 85 km/h, and the angle of the bullet's trajectory. Participants seek clarification on the use of the Pythagorean theorem and the reasoning behind subtracting from 180 degrees in the context of the bullet's motion. The discussion highlights the complexities of analyzing relative motion in this scenario.
auk411
Messages
54
Reaction score
0

Homework Statement



A wooden boxcar is moving along a straight railroad track at speed v1. A sniper fires a bullet (initial speed v2) at it from a high powered rifle. The bullet passes thought both lengthwise walls of the car, its entrance and exit holes being exactly opposite each other as viewed from within the car. From what direction, relative to the track, is the bullet fired from? Assume that the bullet is not deflected upon entering the car, but that its speed is decreased by 20%. Take v1 to be 85 km/h and v2 = 650 m/s.

Homework Equations



3eca9149-c5a9-457f-ab77-365aa4d7a3d5.jpe


The Attempt at a Solution



I don't understand what is going on. Can someone please explain the explanation to me. For example, why is the triangle set up as it is. Why is the hypotenuse the speed of the bullet as it is leaving the boxcar? And why do we have to subtract from 180 degrees.
 
Physics news on Phys.org
I understand that the bullet is fired from an angle that is perpendicular to the track, but I don't understand why we have to use the Pythagorean theorem and why we are subtracting from 180 degrees. Can someone please explain this to me. Thanks!
 

Thread 'Errors and significant figures'

I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
View full post »
Thread 'A cylinder connected to a hanging mass'

Thread 'A cylinder connected to a hanging mass'

Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
View full post »

Similar threads

Shooting a bullet at an angle from a given height
Replies
1
Views
2K
Simple harmonic motion: mass on a spring is hit by a bullet
Replies
6
Views
6K
Momentum of a Bullet Contacting a Block
Replies
9
Views
8K
Conservation of Momentum Problems: Find Final Velocity | Part A, B, C
Replies
8
Views
12K
Relative Motion of a moving sidewalk
Replies
2
Views
5K
What was the bullet's speed as it left the barrel?
Replies
17
Views
8K
HELP Some simple questions from a confused Student
Replies
9
Views
4K
Does Relativity Challenge Our Understanding of Velocity Addition with Tachyons?
Replies
21
Views
6K
What Forces Act on a Car During a Turn and Collision?
Replies
2
Views
4K
Uniform Circular Motion (free-body diagram)
Replies
4
Views
6K

Hot Threads

Recent Insights

Back
Top