An 800 kg car is parked next to a 1000 kg car. Their centers of mass are 3.5 m apart. Find the gravitational force between them.

4.356e-6 Newtons

Explanation:

Using the equation for the force of gravity F=. The two masses are m1=800kg and m2=1000 kg. The value of G, the gravitational constant =6.67e-11. The problem states the distance between the center of masses of the two cars is 3.5 meters(r). Plugging in what we have from the problem, you will get 4.346e-6 newtons. This makes sense as gravity in itself is a weak force requiring extremely massive objects to result in a noticeable force.

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

change in speed = (20-120)= -100 m/s.

1.5 min = 90 sec

acceleration = -100/90 = -1.11 m/s^2.

we don't care about the 150kg or the 2,500 meters. they don't make any difference.

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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.