a truck of mass 150kg is released from rest at point A and moves along a frictionless truck as shown below

Vmax = 34.3[m/s]

Explanation:

We must remember that the definition of energy transformation, which tells us that potential energy is transformed into kinetic energy and vice versa.

Potential energy is defined as the product of mass by gravity by height.

where:

m = mass = 150 [kg]

g = gravity acceleration = 9.81 [m/s²]

h = elevation = 60 [m]

When the height is zero, all the potential energy will have been transformed into kinetic energy, with this kinetic energy we can calculate the velocity.

The maximum kinetic energy is reached in B

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.