Two billion people jump up in the air at the same time with an average velocity of 7.0 m/sec. If the mass of the average person is 60 kilograms and...

Momentum is defined as the product of mass and velocity. That is: `p=mv` . For this example the momentum of the group of humans would therefore be: p=2000000000*60*7=840000000000 kg m/s = 8.4 x`10^(11)` kg m/s

Momentum of a group of objects is simply the sum of the parts. So, the momentum of  2 billion people is equal to 2 billion times the momentum of one person (or the total mass times velocity, as long as the velocities...

Momentum is defined as the product of mass and velocity.
That is: `p=mv` . For this example the momentum of the group of humans would therefore be: 
p=2000000000*60*7=840000000000 kg m/s = 8.4 x`10^(11)` kg m/s

Momentum of a group of objects is simply the sum of the parts. So, the momentum of  2 billion people is equal to 2 billion times the momentum of one person (or the total mass times velocity, as long as the velocities are the same).

 Here because we are assuming that the humans are identical (all 60kg, all jumping at 7m/s) we can restate the equation more simply:
`` (where the subscript 't' is the total amount).

Remember to make sure you're working in SI units, and to include the units of momentum at the end.