Askier of mass 60 kg is pulled up a slope by a motor-driven cable. (a) how much work is required to pull him 75 m up a 30° slope (assumed frictionless) at a constant speed of 2.4 m/s? kj (b) what power (expressed in hp) must a motor have to perform this task?

Explanation:

Given

mass of skier=60 kg

distance traveled by skier=75 m

inclination

speed (v)=2.4 m/s

as the skier is moving up with a constant velocity therefore net force is zero

Force applied by cable

work done

(b)Power

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.