Transcript Matter in Motion

Matter in Motion
Chapter 5 Section Review
Pg 111 #1-4, pg 114 #1-3, pg 118
#1-3, pg 124 #1-4, pg 129 #1-3
Pg 111 #1-4
1. What is a reference point?
An object that appears to stay in place in
relation to an object being observed and is
used to determine if the object is in
motion.
2. What two things must you know to
determine speed?
The distance traveled and the time
taken to travel that distance
Pg 111 #1-4 (cont.)
3. What is the difference between speed and
velocity?
Speed does not include direction; velocity does.
4. Explain why it is important to know a tornado’s
velocity and not just its speed.
It is important to know the velocity
because velocity includes direction.
Knowing only the speed would not tell the
direction that the tornado is traveling.
Knowing the direction of travel would allow
people to avoid or escape it’s path.
Pg 114 # 1-3
1. What is acceleration?
Acceleration is the rate at which velocity
changes.
2. Does a change in direction affect acceleration?
Explain your answer.
Yes, a change in direction does affect
acceleration. Acceleration is a measure
of velocity change. Velocity is speed in a
given direction, and velocity changes if
direction changes.
Pg 114 #1-3 (cont.)
3. How do you think a graph of deceleration
would differ from the graph shown above?
Explain your answer.
The graph showing acceleration has
a positive slope. A graph showing
deceleration would have a negative
slope. The graph would take this
shape because velocity would be
decreasing as time passes.
Pg 118 #1-3
1. Give four examples of a force being exerted.
Kicking a ball, writing with a pencil,
pulling a rope, pushing a stalled car.
2. Explain the difference between balanced and
unbalanced forces and how each affects the
motion of an object.
Unbalanced forces occur when the net force
on an object is not zero; balanced forces occur
when the net force equals zero. Unbalanced
forces cause a change in an object’s motion;
balanced forces cause no change.
Pg 118 #1-3 (cont.)
3. In the picture at left, two bighorn sheep push on
each other’s horns. The arrow shows the
direction the two sheep are moving. Describe
the forces the sheep are exerting and how the
forces combine to produce the sheep’s motion.
Because the sheep are moving as
indicated by the arrow, the forces they are
exerting on each other are unbalanced.
The sheep on the left is exerting a larger
force, so the total net force is in the
direction it is pushing.
Pg 124 #1-4
1. Explain why friction occurs.
Friction occurs because the
microscopic hills and valleys of the
two touching surfaces “stick” to each
other.
2. Name two ways in which friction can be
increased.
Friction can be increased by making
surfaces rougher and by increasing the
force pushing the surfaces together.
Pg 124 #1-4 (cont.)
3. Give an example of each of the following types of
friction: sliding, rolling, and fluid.
Sliding – skiing and writing with a pencil; rolling
– riding a bicycle and pushing a handcart; fluid –
swimming and throwing a softball.
4. Name two ways that friction is harmful and two ways that
friction is helpful to you when riding a bicycle.
Harmful – it causes tire tread to wear
down and the wind can slow you down;
helpful – the wheels grip the road and your
feet and hands stay on the pedals and
handlebars.
Pg 129 #1-3
1. How does the mass of an object relate to the
gravitational force the object exerts on other
objects?
The greater an object’s mass, the larger
the gravitational force it exerts on other
objects.
How does the distance between objects affect the
gravity between them?
As the distance between objects increases, the
gravitational force between them decreases;
as the distance between objects decreases,
the gravitational force between them
increases.
Pg 129 #1-3 (cont.)
3. Explain why your weight would change if you
orbited Earth in the space shuttle but your mass
would not.
A person’s weight decreases in orbit
because the distance between the person
and the Earth would increase. But the
person’s mass would remain the constant,
because mass is the amount of matter in
an object, and it does not depend on
gravitational force.