Two marbles (m = 0.050 kg each) moving on a table towards each other with the speed of 0.3 m/s collide, and start moving away from each other.
a) what is the total momentum of this system before the collision?
v1 = m/s, v2 = m/s,

p1 = kg m/s, p2 = kg m/s,

ptotal = kg m/s

V1 = 0.3 m/s, V2 = -0.3 m/s,

p1 = 0.015 kg m/s, p2 = ___-0.015 kg m/s,

ptotal = _0 kg m/s

Explanation:

Taking the marble ball that moves from right to left as Marble 1 and the one that moves from left to right as Marble 2. We take direction from left to right as negative and from right to left as positive. Therefore, velocity of marble 1 will be +0.3 m/s while velocity of marble 2 will be -0.3 m/s. The mass of marble 1, m2 0.05 Kg and same to marble 2, m2=0.05 Kg

Momentum is product of mass and velocity hence using p to represent momentum

P1=0.05*0.3=0.015 Kg m/s

P2=0.05*-0.3=-0.015 Kg m/s

V1=0.3 m/s, V2=-0.3 m/s

The total momentum before collision will be the sum of P1 and P2 hence 0.015 Kg m/s+-0.015 Kg m/s=0

Ptotal=0 Kg m/s

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.

your answer is c! hope this : )