PhysicsLAB: 2010 Form B

Two small objects, each with a charge of -4.0 nC, are held together by a 0.020-meter length of insulating string as shown in the diagram above. The objects are initially at rest on a horizontal, nonconducting, frictionless surface. The effect of gravity on each object due to the other is negligible.

	(a) Calculate the tension in the string.

	(b) Illustrate the electric field by drawing electric field lines for the two objects on the following diagram.

The masses of the objects are m₁ = 0.030 kg and m₂ = 0.060 kg. The string is now cut.

	(c) Calculate the magnitude of the initial acceleration of each object.

	(d) On the axes below, qualitatively sketch a graph of the acceleration a of the object of mass m₂ versus the distance d between the objects after the string has been cut.

	(e) Describe qualitatively what happens to the speeds of the objects as time increases, assuming that the objects remain on the horizontal, nonconducting, frictionless surface.

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