Question

An electron moving with a velocity of 5* 104 m/s enters into a uniform electric field and acquires a uniform acceleration of 104 m/s² in the direction of its initial motion. calculate the time in which the electron would acquire a velocity double of its initial velocity

Answer 1

Ans. is 5 sec. ... solution is in the pic :)

Answer 2

Answer:

Given initial velocity, u = 5 × 104 m s-1

and acceleration, a = 104 m s–2

(i) final velocity = v = 2 u = 2 × 5 ×104 m s–1 =10 × 104

m s–1

To find t, use v = u + at

or

t=v-u/a

10 ×10 - 5×10 5 ×10 = = 5 s

10 10

(ii) Using s = ut +

1 2 at

2

= (5 ×104) × 5 +

1 4 2 (10 ) × (5) 2 = 25 ×104 +

25 4 ×10

2 = 37.5×104 m