3. Question
2 answers:
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If gravitational effects from other objects are negligible, the speed of the rock at a very great distance from the planet will approach a value of
<u>Explanation:</u>
To express velocity which is too far from the planet and escape velocity by using the energy conservation, we get
Rock’s initial velocity
, . Here the radius is R, so find the escape velocity as follows,
Where, M = Planet’s mass and G = constant.
From given conditions,
Surface potential energy can be expressed as,
R tend to infinity when far away from the planet, so
Then, kinetic energy at initial would be,
Similarly, kinetic energy at final would be,
Here,
Now, adding potential and kinetic energies of initial and final and equating as below, find the final velocity as
'm' and as common on both sides, so gets cancelled, we get as
We know, , it can be wriiten as
, we get
Taking squares out, we get,
Answer:
Coin is dropped from a height of 19.62 m
Explanation:
We have given time t = 2 sec
As coin is drop means its initial velocity u = 0 m/sec
We have to find the height from which coin is dropped
From second equation of motion we know that
So height
So coin is dropped from a height of 19.62 m