Question

V=UTUL
Example 14. An electron travelling with a sheer
5 x 10^3 ms-1 passes through an electric field with a
acceleration of 10^12ms 2. (i) How long will it take for
electron to double its speed ? (ii) What will be the distance
covered by the electron in this time?
​

Answer 1

Answer:

i ) 5× 10^-9s

ii ) 37.5 micro metres or 37.5 ×10^-6 m

Explanation:

let u =5×10^3 m/s

a= 10^12 m/s^2

v = final velocity =2u

t= time taken

s= distance travelled

Using newton laws of motion

v=u+at

2u=u+at

this implies u=at

hence t=u/a = (5×10^3)/(10^12)

t= 5×10^-9 s

also acc. to newton laws of motion

s=(v^2 -u^2)/2a

s= (4u^2- u^2)/2a

s= 3u^2/2a

s= 37.5 ×10^-6m