Answer:
a)
, b) 
Explanation:
a) The final velocity of the 13.5 g coin is found by the Principle of Momentum Conservation:

The final velocity is:

b) The change in the kinetic energy of the 13.5 g coin is:
![\Delta K = \frac{1}{2}\cdot (13.5\times 10^{-3}\,kg)\cdot \left[(11.9\times 10^{-2}\,\frac{m}{s} )^{2}-(0\,\frac{m}{s} )^{2}\right]](https://tex.z-dn.net/?f=%5CDelta%20K%20%3D%20%5Cfrac%7B1%7D%7B2%7D%5Ccdot%20%2813.5%5Ctimes%2010%5E%7B-3%7D%5C%2Ckg%29%5Ccdot%20%5Cleft%5B%2811.9%5Ctimes%2010%5E%7B-2%7D%5C%2C%5Cfrac%7Bm%7D%7Bs%7D%20%29%5E%7B2%7D-%280%5C%2C%5Cfrac%7Bm%7D%7Bs%7D%20%29%5E%7B2%7D%5Cright%5D)

Periodic motion implies that the ride oscillates back and forth. The period is the time it takes to complete one cycle. Therefore it would be the swing.
Answer:
Car A has a velocity of 40 km/hr west.
Explanation:
The velocity of an object is a vector quantity. It has both magnitudes as well as direction.
Arrows are used to show direction.
Car A is moving towards west. Car B is moving towards east-south direction. Car C is moving towards South direction. Car E is moving towards North direction.
So, the correct option is (a) i.e. Car A has a velocity of 40 km/hr west.
The work done by the electric field is equal to the loss of electric potential energy of the proton in moving from its initial location to its final location:

where

is the proton charge,

and

are the voltages in the final and initial locations. Substituting, we get