In the picture below, sphere X swings down and collides with sphere Y. Identify the action and reaction forces.  Action force: 
Reaction force: 

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.

What are some important factors to consider when choosing a warm-up before your workout?

Ajoint produces movement when its angle decreases. which type of movement is it?