The atomic number of Copper is 29. So immediately we know that there are <em>29 protons </em>in the nucleus of each Copper atom, and <em>29 electrons</em> in the cloud surrounding the nucleus of each [neutral] Copper atom.
Copper has two stable isotopes ... ⁶³Copper and ⁶⁵Copper. So if the Copper atom you're holding in your hand is not radioactive, then it has either (63-29)=<em>34 neutrons</em> or (65-29)=<em>36 neutrons</em> in its nucleus. (There's never a need to round the number of neutrons, because there's no such thing as a <em>part </em>of a neutron.)
Answer:
c. 1.11 m/s down
Explanation:
Momentum is conserved.
m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂
Assuming the balloon and projectile are originally at rest:
(90 kg) (0 m/s) + (10 kg) (0 m/s) = (90 kg) v + (10 kg) (10 m/s)
0 kg m/s = (90 kg) v + 100 kg m/s
v = -1.11 m/s
Their "airspeeds" (speed through the air) are equal, but the one traveling in the
same direction as the jet-stream appears to move along the ground faster.
