# Projectile motion problem with upward acceleration and horizontal velocity [closed]

An electron in a cathode-ray tube is traveling horizontally at 2.10×10^9 cm/s when deflection plates give it an upward acceleration of 5.30×10^17 cm/s^2 .

B.) What is its vertical displacement during this time?

I am asking this because the answer my teacher gave is 2.3cm

• For starters, y = y_0 + ut + 0.5at^2, where as you have omitted this 0.5 – Kenshin Feb 7 '13 at 5:24
• And secondly you performed a calculator error as well. See my answer below. – Kenshin Feb 7 '13 at 5:28

$y = y_0 + ut + 0.5at^2$
Since $y_0$ and $u$ are $0$, we have $y = 0.5~at^2$.
In your calculation $t = 2.95 \times 10^{-9}$, which is correct.
So, $y = 0.5\times5.30×10^{17}\times (2.95 \times 10^{-9})^2$
Therefore, $y = 2.3~\text{cm}$