PHY101 Physics Assignment No.2 Solution FALL 2014

Question No:1

Dynamics of simple harmonic motion..

For one-dimensional simple harmonic motion, the equation of motion, which is a second-order linear ordinary differential equation with constant coefficients, could be obtained by means of Newton's second law and Hooke's law.

Question No.2. Solution (a)

A Black hole is anything but empty space. Rather, it is a great amount of matter packed into a very
small area - think of a star ten times more massive than the Sun squeezed into a sphere
approximately the diameter of New York City. The result is a gravitational field so strong that nothing,
not even light, can escape. In recent years, NASA instruments have painted a new picture of these
strange objects that are, to many, the most fascinating objects in space.
Although the term was not coined until 1967 by Princeton physicist John Wheeler, the idea of an
object in space so massive and dense that light could not escape it has been around for centuries.

Question No.2(b) Solution:
The escape velocity of anybody projected upward is as follow:
V=square root (2GM/r)

Where
G is the universal gravitational constant (G = 6.67×10−11 m3 kg−1 s−2
),
M the mass of the planet,
And
r the distance from the center of gravity
According to this formula, the escape velocity is independent of the mass of the escaping object. It
does not matter if the mass is 1 kg or 1,000 kg, what differs is the amount of energy required. For an
object of mass m the energy required to escape the Earth's gravitational field is GM / r.
It depends on the mass of planet (earth).

Question 3 Solution:
The marchers on left will have greater rotational velocity according to following relation:
w=v/r
Where
‘w’ is rotational velocity
‘v’ is linear velocity.
‘r’ is radius from the point of rotation.
here we can justify this case as “r” i-e radius is smallest for the most left marcher as radius &
rotational velocity are inversely proportional to each other.
So
Option A is right.