Than to lift it straight up.
ROPE CLIMBING (2011;3 - AS90940)
A girl of mass 60 kg uses 5 100 J of energy when she climbs a vertical rope.
(a)
Calculate the maximum height it would be possible for the girl to reach.
(b)
In reality, the girl reaches a height of only 8 m.
Explain why the energy used by the girl during the climb does not equal the
work she does to reach the vertical height of 8 m.
In your answer you should:
name the type of energy the girl has when she is 8 m above the ground
calculate the work done to reach a height of 8 m above the ground
calculate the difference between the work done and the energy used by the
girl
•
explain where the "missing" energy has gone, and why this occurs.

Explanation:

(a) PE = mgh

5100 J = (60 kg) (10 m/s²) h

h = 8.5 m

(b) At 8 m, the girl has a gravitational potential energy of:

PE = mgh

PE = (60 kg) (10 m/s²) (8 m)

PE = 4800 J

The difference in energy is 300 J.  This energy is converted into heat in the girl's muscles.

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.

positive reinforcement? ?