- #1

fredrick08

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**[SOLVED] Newton theory of gravity**

## Homework Statement

what are the magnitude and direction of the net gravitational force on the 20kg mass.

Now this is kinda tricky but there is an 20kg ball on the origin, and two 10kg balls 20cm above the x axis, and one is 5cm right and the other is 5cm left of the y axis.

## Homework Equations

F=GMm/R^2

G=6.67x10^-11

## The Attempt at a Solution

F(on m1)=F(m2 on m1)+F(m3 on m1)

F(m2 on m1)=GMm/R^2=(6.67x10^-11*20*10)/0.2^2=3x10^-7

**j**N

F(m3 on m1)=" "=" "=" ' "

Thus F(on m1)=3x10^-7

**j**+3x10^-7

**j**=6.67x10^-7

**j**N

Now i thought this question was kinda straight forward, but in the answers in the book the answer is 3x10^-7

**j**N, half of what i got... and i don't know where i went wrong, can someone please help me?