If the net force acting on an objects doubles, how will the objects acceleration be affected?

The object acceleration also doubles.

Explanation:

Force is a product of mass of an object and its acceleration.

i.e Force = Mass x Acceleration

Let assume for an object

Force applied = ? (unknown value)

Mass of object = K

Acceleration = N

Then, Force = Mass x Acceleration

Force = K x N

Force = KN

However, if the net force is doubled (i.e Force becomes 2KN from 2 x KN), find acceleration

Again, Force = Mass x Acceleration

2KN = K x ?

? = 2KN/K

? = 2N

Now, acceleration is 2N which indicates that it has also doubled. (since it was N before)

Thus, if the net force acting on an object doubles, the object acceleration also doubles.

one person pulls 90n one way and the other has 100n pulling the other way.

so the net force = 90 - 100 = -10n,

or the ans can be 10n if the picture shows -90n and 100n instead.

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.