A car travels north along a straight highway at an average speed of 85 km/h. After driving 2.0 km, the car passes a gas station and continues along the highway. What is the car’s position relative to the start of its trip 0.25 h after it passes the gas station?

   x_total = 23250 m

Explanation:

This is a uniform motion exercise, the equation that describes the motion is

         v = x / t

the position is

        x = v t

let's reduce the magnitude to the SI system

        v = 85 km / h (1000 m / 1km) (1h / 3600 s) = 23.61 m / s

         t = 0.25 h (3600 s / 1h) = 900 s

let's calculate

         x₁ = v t₁

         x₁ = 23.61   900

         x₁ = 21250 m

The distance from the origin is

         x_total = x_station + x₁

         x_total = 2000 + 21250

         x_total = 23250 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.

f is prop to m1xm2 double m1 double force