Question

The earth orbits around the sun because it has angular momentum. If we stopped the earth in orbit and then let it fall straight towards the sun, how long would it take to reach the sun in seconds

Answer 1

some data must be given .. or we have to assume all astronomical data?

Answer 2

ya sorry
The mass of the sun is 2×1030 kg.
The mass of the earth is 6×1024 kg.
Newton's constant is 6.67×10−11 Nm2/kg2.
The earth is 149,600,000 km from the sun.
You may treat the earth and sun as point masses.

Answer 3

hmmm.. still its not all that easy.. cause the force keeps varying.. are you allowed to use calculus? (cause i think thats the only way of doing it :D)

Answer 4

no as earth stops moving the v=0 then only gravitational attraction of sun on earthis occuring

Answer 5

yes but the graviational attraction increases with time, cause the earth is plummeting towards the sun..!!! hence the acceleration is not a constant.. so you can't use your normal 1d kinematic equation!

Answer 6

ya u said correct the we can use the work energy theorem

Answer 7

oh yea.. wait lemme do that!

Answer 8

or we can use conservation of energy.. P.Ei = P.Ef + kinetic energy!.. P.Ei can be calculated.. but P.Ef would be infinite :-/ cause distance would be zero!

Answer 9

it sound stricky gotta think over it i will also think byr thank you for ur help

Answer 10

the first clue is let us calculate the gravitational acceleration on the earth by sun

Answer 11

the gravitational acceleration on the earth by the sun can be found out if we know the radius of the sun by using the formula\[g=GM /R ^{2}\]. the use the simple equation of motion. take initial velocity of the earth as zero.