A ball of mass of 0.5kg is dropped from a height of 2m. Assuming that all of the GPE is transferred to KE, what
will be the velocity of the ball when it hits the ground?

6.3m/s

Explanation:

Given parameters:

Mass of the ball  = 0.5kg

Height  = 2m

Unknown:

Velocity when the ball hits the ground  = ?

Solution:

Since the potential  energy is transformed into kinetic energy;

            P.E  = K.E

              mgh  = m v²

     cancelling m;

               gh  =   v²

                v² = 2gh

                v  = √2gh

Insert the parameters and solve;

               v  = √2gh  = √ 2 x 9.8 x 2  = 6.3m/s

answer: the correct answer is 1.

explanation: there are various process in which a radioactive nuclei decays:

1) alpha decay: in this process, a heavier nuclei decays into lighter nuclei by releasing alpha particle. the mass number is reduced by 4 units.

2) electron capture: in this decay process, a parent nuclei absorbs an electron and gets converted into a neutron. simply, a proton and an electron combines together to form a neutron. mass number does not change in this process.

3) gamma ray emission: it is a decay process in which an unstable nuclei gives excess energy by a spontaneous electromagnetic process. this decay releases . this process does not change the mass number.

4) positron emission: it is a type of decay process, in which a proton gets converted to neutron and an electron neutrino. this is also known as -decay. in this the mass number remains same.

from the above information, we see that only alpha-decay is producing a change in the mass number of the nucleus.

0.19 m/s and 0.45 m/s