A girl drops a rock off a bridge into a river. It hits in 3 seconds how high is the bridge?

Apositive point charge q is fixed on a very large horizontal frictionless tabletop. a second positive point charge q is released from rest near the stationary charge and is free to move. which statement best describes the motion of q after it is released? assume q stays on the table

The focal length of a relaxed human eye is approximately 1.7 cm. when we focus our eyes on a close up object, we can change the refractive power of the eye by about 16 diopters. (a) does the refractive power of our eyes increase or decrease by 16 diopters when we focus closely? explain. (b) calculate the focal length of the eye when we focus closely.

As a pendulum bob swings back and forth several times, the maximum height it reaches becomes less and less. this is because more and more of the pendulum bob's energy is being transformed into a. heat energy b. kinetic energy c. potential energy d. kinetic energy and potential energy