If a spring stores 5j of energy when it is compressed by0.5m, what is the spring constant of the spring?

The membrane surrounding a living cell consists of an inner and an outer wall that are separated by a small space. assume that the membrane acts like a parallel plate capacitor in which the effective charge density on the inner and outer walls has a magnitude of 7.0 × 10-6 c/m2. (a) what is the magnitude of the electric field within the cell membrane? (b) find the magnitude of the electric force that would be exerted on a potassium ion (k+; charge = +e) placed inside the membrane.

To do work, this truck uses energy stored in chemical fuel and an electrical battery. how much total energy does this truck put out?

What is a subatomic particle with a negative charge and very little mass?