Forces and Motion

Exploration

When a figure skater spins he/she uses the positioning of his/her arms to control the speed of the spin/ angular velocity. The angular momentum of the skater is always conserved, no matter the positioning of the arms, and can be represented by the equation L = Iw, where L is angular momentum, I is moment of inertia and w is angular velocity. The moment of inertia is an object’s resistance to change in angular velocity and is related to the distribution of the object’s mass.

Objective

Exploration

An object experiencing a constant net force will experience a constant acceleration. Acceleration is defined as either a change in speed or a change in direction. When an object moves along a curved path it may maintain its speed, however it will be constantly changing its direction of movement. This type of acceleration along a curved path is called centripetal acceleration and is the result of a centripetal force, a force that is directed inward, toward the center of the curvature of the path. Examine the figure below.

Exploration

Angular velocity is the rate of rotation of an object along a specific axes. For example, the blades of a ceiling fan rotate around the fan’s central axis. Angular velocity is often measured in the number of degrees the object rotates every second (°/sec) or the number of complete revolutions every minute (RPM). The PocketLab’s gyroscope measures the angular velocity of the PocketLab about the x-, y-, and z-axis.

Objective

Exploration

We have previously learned that velocity is an object’s rate of change in displacement. Velocity is often measured as meters/second. Angular velocity however, measures the rate of change in the displacement of an object as it moves around a central point.

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

Acceleration of an object is dependent upon two variables – the net force acting on the object and the mass of the object. Using a Full-Atwood’s Machine you will explore the relationship between these variables to understand Newton’s Second Law of Motion.

Objective

Exploration

What is velocity? Velocity is often defined as speed with direction and speed is often defined as how fast or slow an object is traveling. But what exactly does being fast or slow mean? How can we represent an object’s velocity with an equation, graph, or other model? What is acceleration?

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”.

Investigation Purpose 

Using office supplies, students will design, build, test, and iterate on a crash cushion that will reduce the force experienced by a cart as it crashes into a wall.