An umbrella tends to move upward on a windy day because
a. buoyancy increases with increasing wind speed
b. air gets trapped under the umbrella and pushes it up
c. the wind pushes it up
d. a low-pressure area is created on top of the umbrella
e. all of the above

Dao makes a table to identify the variables used in the equations for centripetal acceleration. what quantities belong in cells x and y?

Aspring is used to stop a 50-kg package which is moving down a 20º incline. the spring has a constant k = 30 kn/m and is held by cables so that it is initially compressed 50 mm. knowing that the velocity of the package is 2 m/s when it is 8 m from the spring and neglecting friction, determine the maximum additional deformation of the spring in bringing the package to rest.

If frequency goes up, what happens to wavelength? does it get shorter or longer?