3. How does the centripetal force change when the rubber stopper makes a circular motion
with a smaller radius?​

The centripetal force increases.

Explanation:

Centripetal force is given by ; where .

Given these two equations, we can rewrite the formula for centripetal force as:

As shown, radius is in the denominator, thus, a smaller radius would lead to a larger centripetal force.

adding a(n) to an electric circuit would increase the magnetic field around a wire;

b. solenoid

a solenoid is a type of electromagnet whose purpose is to generate a controlled magnetic field.

if the purpose of the solenoid is instead to impede changes in the electric current, a solenoid can be more specifically classified as an inductor rather than an electromagnet.

d) physical means can be used to separate the components of air.