A boat is moving at the rate of 15.0 meters per second. It’s speed is then decreased uniformly to 3.0 meters per second. It takes 4 seconds for the speed to decrease. What is the magnitude of the deceleration of the car ?

-3 m/s²

Explanation:

The formula for deceleration is given as the change in speed over a period of time

Given that,

Initial speed = 15 m/s

Final speed = 3 m/s

change in speed= 3-15= -12 m/s

Time taken= 4 sec

Deceleration = -12/4 = -3 m/s²

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.