Joe Average throws an apple vertically into the air, and then catches it at the same height. The apple is in the air for 2.5s. What is the apple's velocity the moment it's thrown? (choose the correct number of significant figures for your answer) _m/s

The apple's velocity when it's thrown is 12.25 m/s

Explanation:

Vertical Launch Upwards

In a vertical launch upwards, an object is launched vertically up without taking into consideration any kind of friction with the air.

If vo is the initial speed and g is the acceleration of gravity, the time it needs to reach the maximum height is:

Once it reaches the maximum height, the object takes the same time to go back to the launch point.

The apple thrown by Joe Average takes 2.5 s to complete the whole flight, thus the time it went up is t=2.5/2=1.25 seconds.

From the equation above, we solve for vo:

The apple's velocity when it's thrown is 12.25 m/s

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.

luster is not a good characteristic to use by itself because luster is the property of minerals that indicates how much the surface of a mineral reflects light. the luster of a mineral is affected by the brilliance of the light used to observe the mineral surface.