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How long does it take the particle to hit the y-axis?

  • #1
1. When a particle is at the origin, it has a velocity given by vo = (12i + 15j)ms-1. It has a constant acceleration given by a = (-1.5i + 0.25j) ms-2.
(a) How long does it take the particle to hit the y-axis?
(b) At what point does it hit the y-axis?
(c) What is its velocity at the instant it hits the y-axis?




2. Not certain what to use or how to get started. I have never seen nor done a problem like this before. Please help.



3. Not certain what to use or how to get started. I have never seen nor done a problem like this before. Please help.

Homework Statement





Homework Equations





The Attempt at a Solution

 

Answers and Replies

  • #2
cristo
Staff Emeritus
Science Advisor
8,107
72
This is just a projectile type question, written in vector form. Can you solve projectile questions? If so, then just start out as usual: draw a diagram, then write out the quantities you know in the vertical and horizontal directions, and what you want to find out. Then use an appropriate equation for kinematic motion to solve.

Show some work, and we can help you.
 
  • #3
i'm still very xtremely confused, i honestly don't know how to start it at all
 
  • #4
for the velocity it would be the square root of 15^2 + 12^2? which would be 19? and then for acceleration it would be the sqaure root of -1.5^2 + 0.25^2? which would be 1.5? am I completely off track?
 
  • #5
so no way to help get me started?
 
  • #6
cristo
Staff Emeritus
Science Advisor
8,107
72
You just split things up into x and y components. So, the particle is at x=0, with u_x=12, a_x=-1.5; and at y=0, with u_y=15, a_y=0.25.

What is the x coordinate of the particle when it hits the y axis? Can you construct an equation in terms of x coordinates which will allow you to obtain t?
 
  • #7
1
0
I was actually about to ask the exact question. In this case, would it be sufficient to use only the x component for the acceleration and velocity, since in fact, the particle will hit the y-axis at x=o? I used the function x=x_0+v_xo t+1/2at^2. Then plugged my v_xo value(12ms^-1), my constant acceleration in the x direction(-1.5ms^-2). Then solved for t. Leaving me with t=0s(when the particle started at origin), and t=16s. Does this look about right?
 
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