Y coordinate of a charged particle

[Matt21]

Homework Statement

On the diagram, a charged particle of charge 0.000003 C and mass 0.000007 kg moves across the
electric field 6760 V/m with initial speed 40 m/s. When its x coordinate is 93.3 cm, its y coordinate is (in cm)?

Homework Equations

y=(e*Em*x^2)/(2*m*v^2), where Em is electric field, m is mass and v is speed.

The Attempt at a Solution

Using the equation given, I plugged in all the variables y=(0.000003*6760*93.3)/(2*0.000007*40^2) which gave me 7881 which is not correct. What am I doing wrong? Should I be plugging the charge of an electron (1.60*10^-19)? I'm almost positive this is the equation I need to use to figure it out. Any help would be much appreciated.

 

[NFuller]

y=(0.000003*6760*93.3)/(2*0.000007*40^2)

Your units do not match. $E$ is in V/m and $v_{0}$ is in m/s but your distance $x$ is in cm.

 

[Matt21]

Your units do not match. $E$ is in V/m and $v_{0}$ is in m/s but your distance $x$ is in cm.

Do I need to use distance x in m and then convert my answer for y back to cm? Because I've already done that and it still gives me the wrong answer. y=(0.000003*6760*0.933)/(2*0.000007*40^2)

 

[NFuller]

Do I need to use distance x in m and then convert my answer for y back to cm?

Yes, what was your answer when you did this?

 

[Matt21]

The answer I got was 0.788m which is 78.8cm. It says this is incorrect which doesn't make sense.

 

[NFuller]

This is the correct answer. Is this a computer generated answer or is it written in your textbook?

 

[Matt21]

It is an online prelab question I need to answer. Maybe it has to do with significant figures?

 

[NFuller]

It is an online prelab question I need to answer.

Make sure there isn't some strange formatting issue which is causing the computer to reject your answer, such as having the units being entered a certain way. If you are sure this isn't the case then you should bring this to the attention of your professor. Its not uncommon for these programs to occasionally be programmed with a wrong answer.

 

[Matt21]

Okay sounds good. Thank you very much for your help.

 

[NFuller]

Maybe it has to do with significant figures?

Good point actually. The lowest number of sig figs in the numbers they gave you is one. If the program is checking sig figs then your answer should be 80cm.