Download Chapter 3 - Celina City Schools

Chapter 3
“Motion, Acceleration, & Forces”
Section 1 – Describing Motion
A) ____________ occurs when an object changes its position.
1) Motion is ____________ relative to a reference, a group of objects that are not moving
____________ to each other.
a) An object’s ____________ is its distance and direction relative to one
____________ point in the reference frame.
2) ____________ is the length of the path an object travels.
3) ____________ is the distance and direction of an object’s final ____________ from its
initial position
a) ____________ is a physical quantity that includes both size and direction
B) ____________ the distance an object travels per unit time, is measured as ____________ per
Second (m/s) in SI units
1) Calculation:
speed = ____________ / time
s=d/t
2) Speed ____________ as an object moves from one place to another.
3) ____________ is a speed at a single instant in time
a) Car ____________ measure instantaneous speed
4) ____________ is how quickly an object moved over the entire ____________ it traveled
a) To calculate it, ____________ total distance by the total travel time
C) ____________ is the speed of an object and its direction of motion
1) Like displacement, it is a vector that has ____________, which is the object’s speed, and
has direction
2) Velocity can ____________ if the speed and/or direction of the object changes, can
Change if the speed of the object remains ____________
D) A ____________ - ____________ graph shows the motion of an object over a period of time.
1) We plot time on a(n) horizontal ____________ and distance on a(n) ____________ axis
2) On the graph speed is represented by the ____________, or steepness, of the line
Section 2 – Acceleration
A) ____________ is the change in velocity divided by the ____________ it took for the change to
occur
1) It has a size and direction, so it is a ____________
a) Its size is the change in ____________
b) Its ____________ is the direction of the object’s ____________
2) Acceleration occurs when an object’s ____________ and/or direction of motion changes
a) When acceleration and velocity move in the ____________ direction, speed is
increasing
b) When acceleration and velocity move in opposite directions, speed is ____________
3) For example, the direction of Earth’s ____________ around the Sun is continually
changing, so Earth is ____________
B) If the direction of ____________ of an object doesn’t change, you can calculate its acceleration
as follows:
1) ____________ acceleration = (final velocity – initial velocity) / final time – initial time)
2) ____________ = (vf – vi) / (tf – ti)
3) In SI units acceleration uses ____________ per second squared (m/s2)
4) Acceleration is plotted on ____________ - ____________ graphs
a) We plot an object’s ____________ on the vertical axis
b) We plot an object’s time on the ____________ axis
5) If speed is increasing, final speed is faster than initial ____________ and acceleration is
____________.
a) ____________ is positive on speed-time graph
6) If speed is decreasing, ____________ speed is slower than initial speed and acceleration is
____________
a) Slope is negative on speed-time ____________
7) Multiple steep drops and inversion loops in roller coasters produce large ____________
Section 3 – Motion and Forces
A) ____________, is the push or pull that one object exerts on another object measured in newtons
1) Force causes a change in ____________ or velocities
2) ____________ is created when two or more forces act on an object at the same time
3) Balanced forces are equal in ____________ and opposite in ____________; net force is 0.
4) ____________ are combined forces that cause the ____________ of an object to change.
B) Friction opposes the sliding ____________ of two ____________ in contact.
1) It is an unbalanced force that ____________ the speed of an object
2) ____________ form on bumps and dips in contacting surfaces, causing them to
____________ together.
3) ____________ friction prevents two surfaces in contact from sliding past each other
because force cannot break the microwelds.
4) Sliding ____________ is a force that acts in the ____________ direction to the motion of
a surface sliding on another surface and is then force due to static friction.
5) ____________ friction created when an object rolls over a ____________ is usually a
much smaller force than ____________ friction.
C) ____________ is the frictional force that opposes the motion of objects that move through the air
1) It causes objects to fall with ____________ accelerations and speeds
2) It acts in the direction ____________ to the velocity of an object moving in the air
3) Air resistance on a(n) ____________ depends on it’s speed, ____________, and shape of
the object.
D) ____________ velocity is true when the net force on a falling object from the ____________
force of air resistance and the downward force of ____________ is zero.