Traveling at a speed of 18.5 m/s, the driver of an automobile suddenly locks the wheels by slamming on the brakes. the coefficient of kinetic friction between the tires and the road is 0.630. what is the speed of the automobile after 1.25 s have elapsed? ignore the effects of air resistance.

10.774625 m

Explanation:

t = Time taken

u = Initial velocity

v = Final velocity

s = Displacement

a = Acceleration

g = Acceleration due to gravity = 9.81 m/s²

= Coefficient of kinetic friction = 0.63

m = Mass

f = Frictional force

Equation of motion

The speed of the automobile after the time has elapsed is 10.774625 m

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.