Answer: (a)[tex]F=7(10)^{-7}N[/tex]
(b)[tex]F=1.344(10)^{-6}N[/tex]
(c) The force of Jupiter on the baby is slightly greater than the the force of the father on the baby.
Explanation:
According to the law of universal gravitation, which is a classical physical law that describes the gravitational interaction between different bodies with mass:
[tex]F=G\frac{m_{1}m_{2}}{r^2}[/tex] (1)
Where:
[tex]F[/tex] is the module of the force exerted between both bodies
[tex]G[/tex] is the universal gravitation constant and its value is [tex]6.674(10)^{-11}\frac{m^{3}}{kgs^{2}}[/tex]
[tex]m_{1}[/tex] and [tex]m_{2}[/tex] are the masses of both bodies.
[tex]r[/tex] is the distance between both bodies
Knowing this, let's begin with the answers:
Using equation (1) and taking into account the mass of the father [tex]m_{1}=100kg[/tex], the mass of the baby [tex]m_{2}=4.20kg[/tex] and the distance between them [tex]r=0.2m[/tex], the force [tex]F_{F}[/tex] exerted by the father is:
[tex]F_{F}=6.674(10)^{-11}\frac{m^{3}}{kgs^{2}}\frac{(100kg)(4.20kg)}{(0.2m)^2}[/tex] (2)
[tex]F_{F}=0.0000007N=7(10)^{-7}N[/tex] (3)
Using again equation (1) but this time taking into account the mass of Jupiter [tex]m_{J}=1.898(10)^{27}kg[/tex], the mass of the baby [tex]m_{2}=4.20kg[/tex] and the distance between Jupiter and Earth (where the baby is) [tex]r_{E}=6.29(10)^{11}m[/tex], the force [tex]F_{J}[/tex] exerted by the Jupiter is:
[tex]F_{J}=6.674(10)^{-11}\frac{m^{3}}{kgs^{2}}\frac{(1.898(10)^{27}kg)(4.20kg)}{(6.29(10)^{11}m)^2}[/tex] (4)
[tex]F_{J}=0.000001344N=1.344(10)^{-6}N[/tex] (5)
Now, comparing both forces:
[tex]F_{J}=0.000001344N=1.344(10)^{-6}N[/tex] and [tex]F_{F}=0.0000007N=7(10)^{-7}N[/tex] we can see [tex]F_{J}[/tex] is greater than [tex]F_{F}[/tex]. However, the difference is quite small as well as the force exerted on the baby.