The focus of Lesson 1 is Newton's first law of motion - sometimes referred to as the law of inertia. An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless upon by an unbalanced force.

acted

Explanation:

In order for something to start moving, you need to apply a force to it or something else needs to apply a force to it. That is the same for stopping an object, some force needs to stop it. It could be your hand or it could be gravity.

b.a device that inputs heat into a cool object

c) up is the direction the magnetic force is acting on the charge.