Question

Q.18 How potential energy depends upon the frame of reference?

Q.19
Draw a graph between displacement and time when object is thrown vertically with some velocity and
explain this graph ?

Q.20 What is the angle between two vectors if the ratio of their dot product and cross product is v3?​

Answer 1

1. energy does not depend on frame of reference because it is a consequence of space-time curvature (gravity) and not the position of the observer.
2. I don't know
3. Let A and B are two vectors

dot product of A and B

A.B=|A||B|cosQ

cross product of Aand B

A*B=|A||B|sinQ

now ratio of these

A.B/A*B=|A||B|cosQ/|A||B|sinQ

>cosQ/sinQ=cotQ,

now according to your question ratio is equal to 3^1/2

cotQ=3^1/2

Q=30 degree

your answer is 30degre.

Answer 2

Answer:

The potential energy of a space rocket might be reckoned at zero in outer space, and a large negative value on Earth. ... Either way the energy does not depend on frame of reference because it is a consequence of space-time curvature (gravity) and not the position of the observer.

Let vectors be A and B and angle between them be Ø.

Dot product = |A|*|B|*cosØ

Cross product = |A|*|B|*sinØ

it is given that ratio of dot and cross product is √3

=>cosØ / sinØ = √3

=>tanØ = 1/√3

=> Ø = 30˚