Two Labs and Two Focused Notes
Keshawn-Bubba
Classroom_Presentation_Toolkit_Forces3.pptx
Forces
Section 1
1
Essential Questions
How are force and motion related?
How is the net force on an object determined?
Why is there friction between objects?
What is the difference between mass and weight?
Review Vocabulary
mass: amount of matter in an object
New Vocabulary
force
net force
field
friction
gravity
weight
What is force?
A force is a push or a pull. In both examples, the applied force changes the movement of the ball. Sometimes, it is obvious that a force has been applied. But other forces are not as noticeable.
©Lawrence Manning/Corbis
Friction
Suppose you give a skateboard a push with your hand. After you let go, the skateboard slows down and eventually stops. Because the skateboard’s motion is changing as it slows down, there must be a force acting on it. The force that slows the skateboard is called friction. Friction is the force that opposes the sliding motion of two surfaces that are touching each other.
Gravity
At this moment, you are exerting an attractive force on everything around you—your desk, your classmates, and even the planet Jupiter, millions of kilometers away. This attractive force acts on all objects with mass and is called gravity. Gravity is an attractive force between any two objects that depends on the masses of the objects and the distance between them.
weight
D
momentum
C
friction
B
centripetal force
A
What is the gravitational force exerted on an object called?
Assessment
1.
CORRECT
The centripetal force on the shuttle balances Earth’s gravity.
D
The gravity of Earth and the Sun cancel.
C
The spacecraft is in free fall.
B
Earth’s gravity is much less in orbit.
A
Which explains why astronauts seem weightless in orbit?
Assessment
2.
CORRECT
acceleration
D
inertia
C
unbalanced forces
B
balanced forces
A
Which term best describes the forces on an object with a net force of zero?
Assessment
3.
CORRECT
this book
D
the Sun
C
Earth
B
the Moon
A
Which body exerts the strongest gravitational force on you?
Assessment
4.
CORRECT
A, C, and E
D
C and E
C
B and D
B
A and C
A
The graph shows the speed of a car moving in a straight line. Over which segments are the forces on the car balanced?
Assessment
5.
CORRECT
air resistance
D
momentum
C
friction
B
weight
A
Which of the following is not a force?
Assessment
6.
CORRECT
ipc_txen_field
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