F is up
m g is down
a is up
F - m g = m a
E q = m (g+a)
so E = 2 (10+a) / 8
average speed = 4 m/4 s = 1 meter/s
top speed = 2 m/s
change in speed/time = 2 m/s / 4 s
= (1/2) m/s^2 = a
so E = 2 (10.5)/8 = 2.625
A sphere with a mass of 2kg and a net charge -8 C is released from rest at the bottom of the electric field E. The sphere accelerates upward and travels 4m in 4s. Find the magnitude of the electric field. Use g = 10 m/s2.
I am using m= 2kg, q= -8C, yf= 4m, yo= 0m, t=4s, g=-10
Then I use the formula yf= yo+ vyo*t+(1/2)at^2
Subbing in the values 4= 0+0-8a, so a= -(1/2)
Then a= (Eq/m)-g
So, -(1/2)= (E*-8/2)-10, which solves to E= 0.0125
But that is not even an answer choice.
What should I be doing?
Thank you.
1 answer
1 answer