In refraction, when a wave travels from one medium to another it changes speed.
Correct option is A.
PART a)
As we know that gravitational potential energy is given by the formula

here we can see that gravitational potential energy inversely varies with the distance
so here when distance from the sun is minimum then magnitude of gravitational potential energy is maximum while since it is given with negative sign so its overall value is minimum at that position
So gravitational potential energy is minimum at the nearest point and maximum at the farthest point
PART b)
Since we know that sum of kinetic energy and potential energy is constant here
so the points of minimum potential energy is the point where kinetic energy is maximum which means speed is maximum
So here speed is maximum at the nearest point
Part C)
since gravitational potential energy inversely varies with distance so it's graph will be like hyperbolic graph with distance
Explanation:
In the given situation two forces are working. These are:
1) Electric force (acting in the downward direction) = qE
2) weight (acting in the downward direction) = mg
Therefore, work done by all the forces = change in kinetic energy
Hence,
It is known that the weight of electron is far less compared to electric force. Therefore, we can neglect the weight and the above equation will be as follows.

v = 
= 592999 m/s
Since, the electron is travelling downwards it means that it looses the potential energy.
Linear momentum has to be conserved. It was zero before the thread eas burned ... when nothing was moving ... so the momentum of the masses moving in opposite directions has to add up to zero. ... Momentum = mass times speed. ... In one direction, you have 5 kg times 1/5 m/s= 1 kg-m/s. ... We need 1 kg-m/s in the other direction. ... 7 kg times speed = 1 kg-m/s. ... Can you finish it from here ?
Answer:
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Explanation: