How Do You Calculate Gravitational Force Correctly?

[pookisantoki]

A planet has an euqatorial radius of 7.58 * 10^7 m and mass of 6.15 * 10^26 kg. Compute the acceleration of gravity at the equator of this planet.
I used the formula f=G (m1*m2)/(r^2)

i plugged it into the formula
f= (6.674 *10^-11) (6.15 *10^26)/((7.58 * 10^7)^2)= 7.1437N

accerleration= 7.1437/6.15 *10^26=1.1616 * 10^-26

but the answer is wrong, what am i doing wrong??

 

[rock.freak667]

A planet has an euqatorial radius of 7.58 * 10^7 m and mass of 6.15 * 10^26 kg. Compute the acceleration of gravity at the equator of this planet.
I used the formula f=G (m1*m2)/(r^2)

i plugged it into the formula
f= (6.674 *10^-11) (6.15 *10^26)/((7.58 * 10^7)^2)= 7.1437N

What you did here was calculate GM/r².

Acceleration due to gravity is defined as F/m or simply GM/r². So you found the acceleration due to gravity already, so your 7.1437N is really supposed to be 7.1437m/s²

 

[tomcue]

Your calculation is correct, but the units for acceleration should be expressed as meters per second squared (m/s^2). So the correct answer should be 1.1616 * 10^-26 m/s^2. Also, make sure to double check the units for the gravitational constant (G) and the values for mass and radius to ensure they are in the correct units (kilograms and meters).