What is the answer to this?

You hang a book bag on a spring scale and place the bag on a platform scale so that the platform scale reads 23.7n and the spring scale reads 13.8n. what is the magnitude of the force that earth exerts on the bag?

Describe how the motion of a spring being pushed forward and backward is similar to the motion of air particles in a sound wave.

"if the pressure acting on an ideal gas at constant temperature is tripled, its volume isa) reduced to one-third. b) increased by a factor of three. c) increased by a factor of two. d) reduced to one-half"