How do u calculate gravity?

Question

I'm using the formula F= G*((m1*m2)/r^2)
Since i no the force of gravity is 9.8 m/s on earth, i input earth's mass(5.9742*10^24 kg), my mass(50 kg), and the distance between the earth and me(6.372*10^6 m). The gravitional constant is 6.6742*10^-11 m^3 s^-2 kg^-1, i run the numbers and i end up with 491.0180353 kg m s^-2, not even close the 9.8 m/s, what am i doing wrong?

Answer 1

actually u have calculated the GRAVITATIONAL FORCE between earth and urself and not 'g'. you want to know 'g', which is acceleration due gravity.

u obtained F=491 N (approx)

now apply F=mg where m is your mass and g u want to know

then u get g=F/m= 9.8 m/s^2 thats ur answer.

does this solve your query.

Answer 2

How To Calculate Gravity

Answer 3

9.8 m/s is the approximate acceleration due to gravity on bodies near the surface of the Earth, not the gravitational force on those bodies. You can relate these quantities using the elementary Newtonian equation force = mass * acceleration ( F= ma).

When you set up this equality, (m1*m2*G/r^2 = m1*a, where m1 is your mass, m2 is the mass of the earth, etc), you'll see that m1 (your mass) cancels out and you're left with m2*G/r^2, an equation for the acceleration. If you plug in those same numbers (depending on how many decimals you use), you'll get an answer very close to 9.8 m/s.

Answer 4

The equation you are using from the Newton's theory of Gravitation actually calculates the force(both magnitude and direction) being imparted to each of the point masses under a gravitational field. Now in the scenario where one mass is yous and the other one is that of the earth's, you are actually calculating the force between you and the earth. Which means this is the gravitational force that is pulling you from the centre of the earth.

now 'g' is actually the acceleration and expressed mathematically as g = F/m, F being the gravitational force.
now your calculated value is 491.0180353 kg m s^-2 hence ,
F = 491.0180353 kg m s^-2
and m = 50 kg
hence g= 9.820360706 m s^-2 as expected.

Answer 5

If I understand your question correctly, you are trying to calculate acceleration due to gravity and check. You have calculated only the force between you and earth which is nothing but your weight. That is how weight of a body is defined. It is the force with which the earth attracts the body. This force is given by the formula you mentioned. So divide the answer you got (491.0180353)by 50(your mass) u will get the acceleration due to gravity.

Answer 6

What you have calculated is the force of attraction between you
and the earth, which is the answer - 491 kgm/s**2 that you are
getting. This is entirely correct. Why do you think this answer
should be 9.8 m/s**2 ? 9.8 m/s**2 is the value of g, acceleration due to gravity. This g = GM/R**2 [M=earth's mass, R= earth's radius], and thus g is the force of attraction of the earth on a unit mass, ie. 1 kg. on its surface. The answer that you have obtained is thus g multiplied by your mass in kg, ie. your answer
491 = 9.8 * 50. Hope this solves your dilemma.
- Newton in Kolkata, India

Answer 7

the value 9.8m/s^2, is the acceleration due to gravity ,not the force of gravity.You will get this value, if you divide force by mass,that is g=F/m or g=GM/R^2, whereG is the gravitational constant, M is the mass of the earth and R is the radius .
To calculate the force of gravity , on you,you need to multiply 'g' by your mass , that is nothing but your weight ,which is why you got 491.0180353kg
To make it more clear , what you calculated is your weight , not 'g'

Answer 8

You mentioned that the force of gravity is 9.8m/s^2. This is wrong. This value is the acceleration due to gravity. This is the acceleration with which a body falls due to gravity. The force of gravity can also be calculated as, F=mg (g is acceleration due to gravity). So if you multiply your weight with 9.8, you would get the value which is the same as the value you obtained in your calculation.

Answer 9

9.8 m/s^2 (not m/s) is the acceleration due to gravitation and not the force (just compare the units - force has units of newton)
You've used Newton's Law of Gravitation to calculate the force.
By Newton's Second Law of Motion, we have
F = mg where F is the force, m is your mass, and g is the acceleration due to gravity (approx. 9.8m/s^2)

You'll find that the answer for force of gravity obtained by this method tally with your own answer.

(Another way to look at this is that g = F/m so you divide the answer you got by m which is 50kg to get 9.8)

Answer 10

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RE:
How do u calculate gravity?
I'm using the formula F= G*((m1*m2)/r^2)
Since i no the force of gravity is 9.8 m/s on earth, i input earth's mass(5.9742*10^24 kg), my mass(50 kg), and the distance between the earth and me(6.372*10^6 m). The gravitional constant is 6.6742*10^-11 m^3 s^-2 kg^-1, i run the numbers and i...