A 25 kg box sliding to the left across a horizontal surface is brought to a halt in a distance of 15 cm by a horizontal rope pulling to the right with 15 N tension. Required:
a. How much work is done by the tension?
b. How much work is done by gravity?

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.

Which sound characteristic is not affected by the relative motion of an object

For waves in the ocean, the medium of the waves is a. air b. water c. energy d. a passing boat