Complex Projectile Motion question. Algebra help needed

AI Thread Summary
The problem involves calculating the initial speed of a cow launched from a catapult at a 37-degree angle, covering a horizontal distance of 1375 m and landing 39 m below its starting position. The horizontal motion equation is established, leading to a time of flight expression that incorporates the initial speed. The vertical motion equation is then formulated, but the user struggles to isolate the initial speed variable, v1. Suggestions include using a graphing calculator for easier calculations or simplifying the equations by converting trigonometric functions to decimal values. The discussion emphasizes the importance of careful step-by-step calculations to avoid errors.
DeerHunter
Messages
6
Reaction score
0

Homework Statement


A cow, with a mass of 327 kg, if fired from a medieval catapault, and travels a horizontal distance of 1375 m. It lands in a depression 39 m below its starting position. If it is launched at an angle of 37.0above the horizontal, find its initial speed.

Givens
HOR
dx= 1375
V1x= ?
ax= 0m/s2
v2x=v1x

VER
dy= -39 m
v1y= ?
ay= -9.81m/s2
v2y=?

T=?


Homework Equations


<br /> <br /> x = x_0 + v_0 t + (1/2) a t^2<br /> <br />


The Attempt at a Solution


What I did here was make a equation for time of flight for the horizontal
dx=v1*cos37* t +1/2 at^2
1375=v1x*cos37*t
t= 1372/v1*cos37
I then entered this into my vertical distance
dy=v1y*cos37* t +1/2 at^2
-39=v1*sin37*(1372/v1*cos37) + 1/2 (-9.81)(1372/v1*cos37)^2
Now this equation is where it gets tricky, I am not sure how to solve for v1.
 
Physics news on Phys.org
at that point you should plug into get rid of sin and cos so you are working with decimals and just follow order of operations. if you have a graphing calculator it would make life much easier but if not just plug and chug and go step by step as to not lose anything.
 
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...
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...
Back
Top