Amotor has the electrical energy equivalent to 400. joules of work. it can lift a 5.0 kg mass 2.0 meters. calculate the work done by the motor.

Answer : Work done, W = 98 J.

Explanation :

It is given that,

The electrical energy equivalent to 400. joules of work.

The mass that is lifted by the motor, m = 5 kg

Height, h = 2 m

The work done by the motor is given by :

g is acceleration due to gravity

So, the work done by the motor is 98 J

Hence, this is the required solution.  

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.