As horizontal force of 90.0N is required to push a 75.0kg along a horizontal surface at a constant speed. What is the magnitude of the force of friction?if you answer pls show work thank you

90.0N

Explanation:

According to Newtons second law;

F = ma

\sumFx = max

Fm - Ff = max

Given

Moving force Fm = 90.0N

Ff is the frictional force is the mass

ax is the acceleration = 0m/s^2 (constant speed)

Substitute

90 - Ff = 75(0)

90 - Ff = 0

Ff = 90 - 0

Ff = 90.0N

Hence the frictional force is 90.0N

dopamine..

"it was found that some people who were taking the drug l-dopa to raise their levels of dopamine were developing schizophrenic-like symptoms supporting research a strength of the dopamine hypothesis is that there are many studies which have shown support for the neurochemical explanation."

a and c

c is 100% but i am confused in a