What is the difference between velocity and acceleration

When you push downward on a book at rest on a table, you feel an upward force. does this force depend on friction? defend your answer.

Which changes would result in a decrease in the gravitational force btween two objects? check all that apply

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.