Question

An alpha particle (α), which is the same as a helium-4 nucleus, is momentarily at rest in a region of space occupied by an electric field. The particle then begins to move. Find the speed of the alpha particle after it has moved through a potential difference of −3.45×10−3 V .The charge and the mass of an alpha particle are qα = 3.20×10−19 C and mα = 6.68×10−27 kg , respectively.
Mechanical energy is conserved in the presence of which of the following types of forces? (Select all that apply.)

(A) electrostatic
(B) frictional
(C) magnetic
(D) gravitational

Answer 1

Answer:

$v = 0.57 \times 10^3 m/s$

Mechanical energy is conserved in the presence of following forces:

a) electrostatic force

b) magnetic force

c) gravitational force

Explanation:

Give data:

potential difference , $V = - 3.45 \times 10^{-3} V$

we Know change in potential energy is given as

$U = V\times Q$

$U = - 3.45 \times 10^{-3} \times 3.2\times 10^{-19}$

$U = - 1.10 \times 10^{-21} J$

therefore, change in potential energy U is $U = - 1.10 \times 10^{-21}J$

let  speed of particle is  v

from energy conservation theorem

loss of electrical PE = KE gained

$1.1\times 10^{-21} = 0.5 \times 6.68 \times 10^{-27} \times v^2$

solving for v

$v = 0.57 \times 10^3 m/s$

Mechanical energy is conserved for following forces:

a) electrostatic force

b) magnetic force

c) gravitational force