Question

The student with mass 70 ke is sitting in the front row in physics class. The instructor with mass 90 kg is standing 3.0 m in front of the student

Answer 1

Part A)

$F_{instr}=\frac{G*m_{instr}*m_{student}}{d^{2}}$

$F_{instr}=\frac{6.674*10^{-11}*90kg*70kg}{(3m)^{2}}$

$F_{instr}=\frac{6.674*10^{-11}*90*70}{3^{2}}$

ANSWER: ${\color{Red} F_{instr}=4.672*10^{-8}N}$

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Part B)

Gravity Force exerted on the student by earth is the weight of the student

So $\frac{F_{instr}}{F_{earth}}=\frac{4.672*10^{-8}N}{W_{student}}=\frac{4.672*10^{-8}N}{m_{student}*g}$

$\frac{F_{instr}}{F_{earth}}=\frac{4.672*10^{-8}N}{70kg*9.81m/s^{2}}$

$\frac{F_{instr}}{F_{earth}}=\frac{4.672*10^{-8}}{70*9.81}$

ANSWER: ${\color{Red} \frac{F_{instr}}{F_{earth}}=6.804*10^{-11}}$

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