Physical Science –
Chapter 3 Study Guide Answers
Distinguish between distance and
displacement. (Know the definitions)
• Distance = how far (scalar quantity)
• Displacement = distance and direction of an
object (vector quantity)
Calculate the average speed of an
object. (Know the equation)
• Average speed = total distance traveled
divided by total time
Explain the difference between speed
and velocity.
• Speed = distance an object travels per unit of
time (scalar)
• Velocity = speed and direction of a moving
object (vector)
Describe how acceleration, time and
velocity are related.
• Acceleration = change in velocity over time
• Acceleration = final velocity minus initial
velocity divided by time
Explain how positive and negative
acceleration affect motion.
• Positive acceleration = speeding up, upward
movement on the graph
• Negative acceleration = slowing down,
downward movement on the graph
Write equations for the displacement
and velocity of an object over time.
• Velocity = displacement divided by time
• Acceleration = change velocity divided by time
Recognize and draw graphs of an
objects displacement and velocity
verses time.
– Displacement vs. Time = VELOCITY GRAPH
• Time Is on X—axis, Displacement is on Y-axis, Slope =
velocity
– Velocity vs. Time = ACCELERATION GRAPH
• Time is on x-axis, velocity is on y-axis, slope =
Acceleration, area below line is displacement
Interpret motion diagrams
– Drawings to demonstrate
direction of motion, include
forces if known
Explain how forces and motion are
related.
• In order to have motion you need an
unbalanced force
Compare and contrast static friction
and sliding friction.
• Static friction = frictional force prevents 2
surfaces from sliding past each other
Compare and contrast static friction
and sliding friction.
• Sliding friction = force that acts in opposite
direction to the motion of a surface sliding
past another surface
Compare and contrast static friction
and sliding friction.
• Same = both involve surfaces, cause friction
which generates heat
• Different = Static prevents sliding,
– Sliding opposite direction of motion
Describe the effects of air resistance
on falling objects.
• Air Resistance is a form of friction
• Caused by the interaction between an object
and the air molecules it comes into contact
with
Describe the effects of air resistance
on falling objects.
• The bigger the object the more air resistance
• The faster the object the more air resistance
• Without air resistance all objects fall at the
same acceleration
Define motion
• Occurs when an object changes position
Define instantaneous speed.
• Speed of an object at a given point in time
Identify situations when distance and
displacement are the same and
situations when they are different.
• Same – if you start and finish in different
locations
• Different – if you start and finish at the same
spot
Explain what happens if 2 objects have
the same speed but different
velocities.
• Objects are travelling at the same speed but
moving in different directions, or changing
directions
Define acceleration.
• Change in velocity divided by time
When does acceleration occur?
• Anytime there is a change in velocity (slow
down, speed up, change directions)
What does the slope of a distance vs.
time graph represent?
• Speed/velocity
What does the slope of a velocity vs.
time graph represent?
• Acceleration
Define balanced force, unbalanced
force, and net force.
• Balanced force = forces equal in size but
opposite in direction, cancel each other out
• NO CHANGE IN MOTION
Define balanced force, unbalanced
force, and net force.
• Unbalanced force = forces that are not equal
in size and/or direction, combine to produce a
net force that is not zero, can cause the
motion of an object to change
Define balanced force, unbalanced
force, and net force.
• Net force = when 2 or more forces act on an
object at the same time, sum of all the forces
acting on an object