Question

Can someone help me in explaining how I could illustrate this situation with diagrams (system diagrams, force diagrams etc)

• There is a glass marble placed on a slopes ramp. At the bottom of the ramp, unfairly charged spheres in a semicircle are placed. An electric force will be used to hold a marble still. Each sphere has a certain charge that keeps the marble in place in the middle of the ramp.

What would the force diagram look like (what charges? Fg(mgsin0), Couloumbic force etc). Is there any other ways I can illustrate this situation to show what’s going on? Thanks!

Answer 1

Looking at the diagram, we see that several forces are acting on the glass marble:

• Coulomb's force Fc,
• Force of gravity mg
• Normal force N

Pay attention: Coulomb's force is a resultant of all coulomb's forces caused by the charges spheres fixed in a semicircle. Then simply calculate the equilibrium using Newton's second law (use y- and x-axes) and you can find either mass of the marble or Coulomb's force required to keep it in the resting state.