Look at the chart that shows the distance of the star Proxima Centauri from the Earth. Distance from Earth to Proxima
Centauri, the next nearest star
~40,000,000,000,000 km
or
~4.24 light-years
Which of the following would be true if Proxima Centauri was one light year closer to the Earth?
A Its brightness in the sky would appear to be the same as it was before.
B Its brightness in the sky would be reduced because of the orbit of other planets.
It would affect the gravitational pull of the Earth's orbit.
D It would look brighter than the sun.

force is based upon mass and acceleration.the statement is not always true.

it can be explained from newton's second law of motion.

as per newton's second law of motion the rate of change of momentum is directly proportional to the applied force and takes place along the direction of force.

mathematically it can be written as -

                                              ⇒      

here   k is the proportionality constant whose value is 1.

                                                            [a is the acceleration=dv/dt]

hence we see that force not only depends on mass and acceleration but also on velocity and rate of change of mass. force f will depend on mass and acceleration only when mass is constant.

hence the statement that force is based upon mass and acceleration is false.

it is given that trillions of microbes make up to 1% to 3% of the body mass.

let's take average of this percentage: 2%

consider the average mass of the human body as 70 kg.

then, trillions of microbes would have mass  

therefore, 100 trillion micro-organisms would weigh:

this is an approximate value and could change depending on the mass of the human body and percentage of the microbes present in it.

average mass per microorganism =

magnets not strong enough

explanation: