You can determine which charge has the solid by rubbing plastic and fur, and bringing near the plastic and the solid to determine if they are repeled or attracted. If they are repeled, the solid is charged negatively and if they are attracted, the solid is charged positively.

Explanation:

In order to determine the charge of the solid (negative or positive) using a piece of plastic and fur, you have to rubb the plastic with the fur (this is charging by friction)

Negative charges are transferred from the fur to the piece of plastic, therefore the plastic is charged negatively.

Then, you have to bring near the solid and the plastic. If them are repeled, it means that the solid is charged negatively (Because similar charges are repeled)

If them are attracted, it means that the solid is charged positively (Because opposite charges are attracted)

3 0

3 years ago

A uniform disk is constrained to rotate about an axis passing through its center and perpendicular to the plane of the disk. If

katrin2010 [14]

A uniform disk is constrained to rotate about an axis passing through its center and perpendicular to the plane of the disk. If the disk starts from rest and is then brought in contact with a spinning rubber wheel, we observe that the disk gradually begins to rotate too. If after 35 s of contact with this spinning rubber wheel, the disk has an angular velocity of 4.0 rad/s, find the average angular acceleration that the disk experiences. (Assume the positive direction is in the initial direction of rotation of the disk. Indicate the direction with the sign of your answer.)

Assume after 35 s of contact with this spinning rubber wheel, the disk has an angular velocity of 11.0 rad/s.

Answer:

385 rad

Explanation:

The expression for the angular acceleration of a disk that is in contact with a spinning wheel can be given as:

$\alpha = \frac{\delta \omega}{\delta t}$