The given question is incomplete. The complete question is as follows.
In a nuclear physics experiment, a proton (mass 
kg, charge +e = 
C) is fired directly at a target nucleus of unknown charge. (You can treat both objects as point charges, and assume that the nucleus remains at rest.) When it is far from its target, the proton has speed 
m/s. The proton comes momentarily to rest at a distance 
m from the center of the target nucleus, then flies back in the direction from which it came. What is the electric potential energy of the proton and nucleus when they are 
m apart?
Explanation:
The given data is as follows.
Mass of proton = 
kg
Charge of proton = 
Speed of proton = 
Distance traveled = 
We will calculate the electric potential energy of the proton and the nucleus by conservation of energy as follows.
= 
where, 
U = 
Putting the given values into the above formula as follows.
U =
= 
= 
Therefore, we can conclude that the electric potential energy of the proton and nucleus is .
What a relief ! That gives her time to step out of the way, before the ball
comes crashing down in the same place where she was standing.
If net external force acting on the system is zero, momentum is conserved. That means, initial and final momentum are same → total momentum of the system is zero.
Explanation:
Christmas tree production occurs worldwide on Christmas tree farms, in artificial tree factories and from native strands of pine and fir trees. Christmas trees, pine and fir trees purposely grown for use as a Christmas tree, are grown on plantations in many western nations, including Australia, the United Kingdom and the United States. In Australia, the industry is relatively new, and nations such as the United States, Germany and Canada are among world leaders in annual production.
Great Britain consumes about 8 million trees annually, while in the United States between 35 and 40 million trees are sold during the Christmas season. Artificial Christmas trees are mostly produced in the Pearl River delta area of China. Christmas tree prices were described using a Hotelling-Faustmann model in 2001, the study showed that Christmas tree prices declined with age and demonstrated why more farmers do not price their trees by the foot. In 1993, economists made the first known demand elasticity estimates for the natural Christmas tree market.
