Can someone clarify some things for me?

  • Thread starter Thread starter matt@USA
  • Start date Start date
AI Thread Summary
The discussion focuses on clarifying the definitions of variables in 2D motion equations, particularly x, y, V, and Vnaught. X and y represent positions along their respective axes, determined by the user. V denotes the velocity of an object, while Vnaught signifies the initial velocity at time t=0. The conversation also emphasizes the use of subscripts to differentiate components in vector equations. The example provided illustrates how to calculate the final velocity of an object in free fall using the appropriate kinematic equation.
matt@USA
Messages
25
Reaction score
0
I don't know if I am just looking too much into the problems or what, but I am having a very hard time determining what is what in the problems. I am not confident on what I pick as Vnaught, V, x, y, etc ... Will someone please help?
I will tell you how I determine it, and you can correct me.

x=where it lies on the x axis?
y=where it lies on the y axis? ... Both of these are determined by me? Correct?

So is V the velocity of the object? And what is Vnaught?

These are all pertaining to 2D equations.
 
Physics news on Phys.org
Naught is usually the initial value of something. If you have a position graph then you could say that x naught is the starting position of the object. You see subscripts used a great deal. i usually denotes an initial value as well, f usually means the final value. Aside from that everything else is pretty descriptive. When you are dealing with 2+d problems, you might see subscripts of x and y to let you know which component it is. Say you have a vector r, they might say that a_{rx} is the acceleration of the x component of the r vector and so on.
 
Last edited:
Yes, x and y are positions, measured along their respective coordinate axes.

v is velocity. In general it varies with time (i.e., pick a time t, and you'll get a specific value for v).

v0 is initial velocity (i.e. velocity at t = 0).
 
So what is V?
 
matt@USA said:
So what is V?

In the context you have provided, V would be the velocity at the time to are dealing with.

Vo is the initial velocity. V is the velocity later.

eg: you might want to know "if a stone is thrown vertically down from the top of a 30m tower with a velocity of 2 ms-1, how fast will it be traveling just before it hits the ground -[take g=10].

everything is happening downwards, so let down be positive.

Vo = 2.0
a = 10
x = 30
V = ??

Best formula to use would be

V2 = Vo2 + 2as

V2 = 4 + 2x10x30 = 604

so V = 24.6
 
Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .
TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
Back
Top