A tetherball is tied to the end of a 2.1-m string of negligible mass. The ball is struck so that it moves in uniform circular motion in a horizontal plane, and the string makes an angle of 26°
with the vertical pole. The mass of the ball is 1.3 kg. What is the tension in the string?

Let t denote the magnitude of the tension in the string and w the weight of the ball. We have

w = (1.3 kg) g = 12.74 N

where g = 9.80 m/s² is the magnitude of the acceleration due to gravity.

In the vertical direction, the ball is in equilibrium, so that, by Newton's second law, we have

t cos(26º) - w = 0

Solving for t gives

t = w sec(26º) ≈ 14 N

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.

gravitational energy

electrical energy

kinetic energy

ligh energy