Physics, 24.10.2019 04:00 lilGi0

Two identical cars are driving in opposite directions at the same speed. their kinetic energies have

a. different magnitudes and opposite signs

b. different magnitudes, but the same sign

c. the same magnitude and sign

d. the same magnitude, but opposite signs

Answers: 2

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Answer from: abdirahmansoloman

The right answer is c.

Explanation:

The kinetic energy is defined as follows:

K = 1/2 mv²

If both cars are identical, this means that they have the same mass.

Also, we are told that the speed is also the same for both cars.

If they are going in opposite directions, their velocities have the same magnitude, but opposite signs.

But even though they have different signs, the square (which is the parameter relevant for kinetic energy calculations), is always positive, as any number, elevated to an even power, is positive.

So, we conclude that both cars have the same kinetic energy, in magnitude and in sign.

Answer from: Quest

depends on what you mean by "group." for order, it would be coleoptera (beetles). for class, it would be insecta (insects). for phylum, it would be the arthropoda (animals with jointed exoskeletons).

explanation:

Answer from: Quest

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.

$_a^z\textrm{x}\rightarrow _{a-2}^{z-4}+_2^4\alpha$

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.

$_a^z\textrm{x}+_{-1}^0\textrm{e}\rightarrow _{z-1}^a\textrm{y}$

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 $\gamma -radiations$ . this process does not change the mass number.

$_a^z\textrm{x}^*\rightarrow _a^z\textrm{x}+_0^0\gamma$

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 $\beta ^+$ -decay. in this the mass number remains same.

$_a^z\textrm{x}\rightarrow _{z-1}^a\textrm{y}+_{+1}^0e$

from the above information, we see that only alpha-decay is producing a change in the mass number of the nucleus.

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Two identical cars are driving in opposite directions at the same speed. their kinetic energies have...