Hi everyone! Im really bad in physics so I need help in my assignments. My problem is what formula to use. Here's the problems.(adsbygoogle = window.adsbygoogle || []).push({});

1. The problem statement, all variables and given/known data

An electron (mass = 9.11 x 10^{-31}kg) leaves one end of a tv picture tube with zero (0) initial speed and travels in a straight line to the accelerating grid, which is 1.80 cm away. It reaches the grid with a speed of 3.00 x 10^{06}m/s; If the accelerating force is constant, compute:

a.) acceleration

b.) time to reach the grid

c.) net force in Newtons (gravitational force on the electron may be neglected)

given:

m = 9.11 x 10^{-31}

v_{o}= 0 m/s

v_{F}= 3.00 x 10^{06}

d = 1.80 cm = 0.018m

In A:

I've thought of two formulas. Both give different results. These are:

a = v/t

Since there is no TIME, I will have to solve for time using:

t = m(v - v_{o}) / F

The other formula I have thought of is:

a = v^{2}/ 2x (from v^{2}= v_{o}^{2}+ 2ax)

In B:

It's either:

t = m(v - v_{o}) / F

or

t = d/v

both giving different results again

In C:

It's obviously F = ma...

Please help me, I really don't know what formula to use.

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# Homework Help: Newton's Laws of Motion problem help

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