Homework Help

Question

An electron in a cathode-ray-tube (CRT) accelerates
at a constant rate from 17800 m/s
to 4.18 × 106 m/s over 1.02 cm.
How long does the electron take to travel
this distance?

Answer 1

I will set up the solution for you, but YOU do the calculations.

 

a = constant ⇒

 

v(t) = v₀ + at ⇒

 

t = [v(t) - v₀]/a

 

Get a from kinematics.

 

v² - v₀² = 2ad ⇒

 

a = (v² - v₀²)/(2d)

 

Plug in

 

v = 4.18 x 10⁶ m/s

v₀ = 17,800 m/s

d = 0.0102 m

 

and get a in m/s².  Then plug a, v, and v₀ into

 

t = (v - v₀)/a

 

and get t in seconds.  You should be able to finish from here.