An electron accelerates from rest at a rate of 15000 m/s by an electric field between two plates that have a voltage of 20000 V. How fast is the electron moving after 3 ms.
I solved this, and got an answer of 45 m/s (a=v/t), but the answer (proposed by my teacher) is .045 m/s. Why am I wrong?

Question

An electron accelerates from rest at a rate of 15000 m/s by an electric field between two plates that have a voltage of 20000 V. How fast is the electron moving after 3 ms.
I solved this, and got an answer of 45 m/s (a=v/t), but the answer (proposed by my teacher) is .045 m/s. Why am I wrong?

anonymous · Answer

Assuming the 15000 is m/s/s then the answer you have looks right. The question seems quite strange as for that voltage and acceleration (assuming flat plates) the plate separation would be huge (E11 m!!) so I suspect there is a stuff up somewhere.