To determine Kelly's weight in newtons when her mass is 70 kilograms, we need to use the formula for weight, which is:
[tex]\[ \text{Weight} = \text{mass} \times \text{acceleration due to gravity} \][/tex]
Given the mass [tex]\( m = 70 \)[/tex] kg and the acceleration due to gravity [tex]\( g = 9.8 \)[/tex] m/s², we multiply these values together to find her weight.
[tex]\[ \text{Weight} = 70 \, \text{kg} \times 9.8 \, \text{m/s}^2 \][/tex]
When you perform the multiplication:
[tex]\[ \text{Weight} = 686.0 \, \text{newtons} \][/tex]
Thus, Kelly's weight is 686.0 newtons.
The correct answer corresponds to the expression [tex]\( 70 \times g \)[/tex].
So, the correct answer is:
A. [tex]\( 70 \times g \)[/tex]