Two identical metal spheres are firmly fastened to and electrically insulated from frictionless plastic air pucks that ride on an air table as shown below. The pucks are held in place as a charge of 2.0e-8 C is placed on sphere A on the left and a charge of 6.0e-6 C is placed on sphere B on the right. The pucks are then released so that the pucks with the spheres attached are now free to move without across the table.
A. Draw free-body diagrams for the pucks and spheres a moment after the pucks are released, showing the forces on all four objects.
Hints for free-body diagrams:
- Represent each object as a point.
- Draw force arrows outward from the point
- If forces are equal, draw arrows of equal length and if the forces are not equal, show the larger forces with longer arrows to some reasonable scale.
- Label each force by the type of force FsubE and with subscripts
indicating which object is exerting the force and which object is being
acted on.
For example:
denotes that A is exerting (pushing or pulling) an electric force on B
B. How do the Coulomb forces acting on spheres A & B compare?
(Compare using a ratio)
C. Which sphere has the greater acceleration? How would your answer change if the mass of the puck under sphere A was reduced by 50%?
D. As the two spheres get farther away from one another, how would (if at
all) the following quantities change?
1. Force
2. Speed
3. Acceleration