Types of Interactions

NGSS Alignment: MS-PS2-3

The disciplinary core idea behind this standard is PS2.B: Types of Interactions. It specifically looks at electric and magnetic forces and how they can be attractive or repulsive, and how the size of the force can depend on the magnitudes of the charges, currents, or magnetic strengths involved. The strength can also depend on the distances between the interacting forces. 

Exploration

When an object is in free fall, the only force acting on the object is gravity. In general terms, an object moving upward is not considered “falling,” however, if gravity is the only force acting on the object (air resistance being negligible) then the object is in fact in a state of free fall. The projectile motion of an object is the trajectory of an object in free fall near Earth’s surface after being thrown or launched in the air. The curved path of the projectile is under the effect of gravity only after being launched.

Exploration

Galileo Galilei is often considered one of the founders of modern science. This is because he investigated questions through experimentation and observations. One of his most famous experiments involved dropping cannonballs of different mass to determine whether they would accelerate to the ground at different rates.

Exploration Part 1

Previously you learned that the net force acting on an object is related to the object’s motion. The net force determines whether the velocity of an object will change. This is described in Newton’s First Law of Motion:

“An object at rest will remain at rest or an object in motion will remain in uniform motion unless acted upon by an outside force”.