#### Science - 2018-19

# PH.5 - Mass, Distance, Force, and Time

The student will** investigate **and** understand** the
interrelationships among mass, distance, force, and time through mathematical
and experimental processes. Key concepts include

a) linear motion;

b) uniform circular motion;

c) projectile motion;

d) Newton’s laws of motion;

e) gravitation;

f) planetary motion; and

g) work,
power, and energy.

**Bloom's Levels:**Analyze; Understand

*Adopted: 2010*

### BIG IDEAS

- I can determine how long it would take me to walk to the mall.
- I can explain why roller coasters don't fall off the track when they go upside down.
- I can explain how rockets work.
- I can explain why I get "thrown" to one side in the car on a sharp turn.
- I can explain why two objects falling from the same height will hit the ground at the same time.
- I can explain why the Earth stays in orbit.
- I can explain how machines have revolutionized the world.

### UNDERSTANDING THE STANDARD

The concepts developed in this standard include the following:

- Newton’s three laws of motion
are the basis for understanding the mechanical universe.
- Linear motion graphs include
- displacement (d) vs. time (t)
- velocity (v) vs. time (t)
- acceleration (a) vs. time (t)
- Position, displacement,
velocity, and acceleration are vector quantities.
- Motion is described in terms of
position, displacement, time, velocity, and acceleration.
- Velocity is the change in
displacement divided by the change in time. A straight-line, position-time
graph indicates constant velocity. The slope of a displacement-time graph is
the velocity.
- Forces are interactions that can
cause objects to accelerate. When one object exerts a force on a second object,
the second exerts a force on the first that is equal in magnitude but opposite
in direction.
- An object with no net force
acting on it is stationary or moves with constant velocity.
- Acceleration is the change in
velocity divided by the change in time. A straight-line, velocity-time graph
indicates constant acceleration. A horizontal-line, velocity-time graph
indicates zero acceleration. The slope of a velocity-time graph is the
acceleration.
- The acceleration of a body is
directly proportional to the net force on it and inversely proportional to its
mass.
- In a uniform vertical
gravitational field with negligible air resistance, horizontal and vertical
components of the motion of a projectile are independent of one another with
constant horizontal velocity and constant vertical acceleration.
- An object moving along a circular
path with a constant speed experiences an acceleration directed toward the
center of the circle.
- The force that causes an object
to move in a circular path is directed centripetally, toward the center of the
circle. The object’s inertia is
sometimes falsely characterized as a centrifugal or outward-directed force.
- Weight is the gravitational
force acting on a body.
- Newton’s Law of Universal
Gravitation can be used to determine the force between objects separated by a
known distance, and describes the force that determines the motion of celestial
objects. The total force on a body can be represented as a vector sum of
constituent forces.
- For a constant force acting on
an object, the impulse by that force is the product of the force and the time
the object experiences the force. The impulse also equals the change in
momentum of the object.
- Work is the mechanical transfer
of energy to or from a system and is the product of a force at the point of
application and the parallel component of the object’s displacement. The net
work on a system equals its change in velocity.
- Forces within a system transform
energy from one form to another with no change in the system’s total energy.
- For a constant force acting on
an object, the work done by that force is the product of the force and the
distance the object moves in the direction of the force. The net work performed
on an object equals its change in kinetic energy.
- Power is the rate of doing work.

### ESSENTIALS

In order to meet this standard, it is expected that students will

a) construct and analyze displacement (d) vs. time (t), velocity (v) vs. time (t), and acceleration (a) vs. time (t) graphs.

solve problems involving displacement, velocity, acceleration, and time in one and two dimensions (only constant acceleration).

b) distinguish between centripetal and centrifugal force.

describe the forces involved in circular motion.

c) resolve vector diagrams involving displacement and velocity into their components along perpendicular axes.

draw vector diagrams of a projectile’s motion. Find range, trajectory, height of the projectile, and time of flight (uniform gravitational field, no air resistance).

solve problems related to free-falling objects, including 2-D motion.

d) solve problems involving force (F), mass (m), and acceleration (a).

solve problems involving multiple forces, using free-body diagrams.

e-f) solve problems using Newton’s Law of Universal Gravitation.

g) solve problems involving mechanical work, power, and energy.

### KEY VOCABULARY

*Updated: Dec 01, 2017*