Atrain traveling at 50 miles per hour has to slow down to 10 miles per hour in 4 seconds. what is the acceleration

Acceleration = (change in speed) / (time for the change)

Change in speed = (speed at the end) - (speed at the beginning)

Change in speed = (10 mph) - (50 mph) = -40 mph

Acceleration = (-40 mi/hr) / (4 sec)

Acceleration = -10 mi/hr-sec

To get a more comfortable, familiar unit for the answer . . .

Acceleration =

(-10 mile/hour-second) x (1,609.3 meter/mile) x (1 hour / 3,600 sec)

Acceleration = (-10 x 1,609.3 / 3,600) (mile-meter-hour / hour-sec-mile-sec)

Acceleration = -4.47 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.