An α-particle has a charge of +2e and a mass of 6.64 10-27 kg. it is accelerated from rest through a potential difference that has a value of 1.24 106 v and then enters a uniform magnetic field whose magnitude is 2.50 t. the α-particle moves perpendicular to the magnetic field at all times.

Explanation:

It is given that,

Charge of alpha particle,

Mass of the alpha particle,

Potential difference,

Magnetic field, B = 2.5 T

The α-particle moves perpendicular to the magnetic field at all times. The initial speed of the alpha particle is 0 as it is at rest. Using the conservation of energy as :

is the speed of the  α–particle

So, the speed of alpha particle is . Hence, this is the required solution.

note: the given question is incomplete.

complete question is given below.

which is an example of kinetic energy?

a. the energy stored in ethanol  

b. a hockey puck sliding across the ice  

c. a compressed spring  

d. a ball sitting at the top of a ramp

solution: the kinetic energy is the energy posses by the virtue of the motion of the object.

in the given options, a, c and d are the example of potential energy because it is the energy posses by the virtue of the rest of the object. but option b has the kinetic energy as the object is in motion.

hence, a hockey puck sliding across the ice   is the apex example of kinetic energy.

so, the option (b) a hockey puck sliding across the ice   is the correct option.