Download Newton`s 2nd Law WebPkt

Physics
Name ___________________________
Newton’s Second Law
Period _____
Use the following site to answer the questions below.
http://www.glenbrook.k12.il.us/gbssci/phys/Class/newtlaws/n
ewtltoc.html
HTTP://WWW.GLENBROOK.K12.IL.US/GBSSCI/PHYS/CLASS/NEWTLAWS/N
EWTLTOC.HTML
Lesson Three
1.
Newton’s Second Law States
The _______________ of an object as produced by a net force is directly
proportional to the magnitude of the net force, in the same direction as the
net force, and inversely proportional to the mass of the object.
2.
Newton’s Second Law in a formula is
_______________
3.
The units for F are (give an equation showing the
unit and what it is equivalent to.)
_________________________
4.
Complete the table below
Force in
newtons
10
20
20
10
Mass in
kilograms
2
2
4
2
Acceleration
in m/s/s
5
10
5.
Consider the two ticker tape traces below for an acceleration of a car. From the
trace, determine the direction of the net force which is acting upon the car. Show with an
arrow on the diagram the direction of the force.
6.
What acceleration will result when a 12-N net force applied to a 3-kg object? A 6kg object?
________
7.
A net force of 16 N causes a mass to accelerate at a rate of 5 m/s2. Determine the
mass.
____________
8.
An object is accelerating at 2 m/s2. If the net force is tripled and the mass is
doubled, then what is the new acceleration?
_____________
9.
An object is accelerating at 2 m/s2. If the net force is tripled and the mass is
halved, then what is the new acceleration?
_____________
10.
Are You Infected with the Misconception?
Two students are discussing their physics homework prior to class.
They are discussing an object which is being acted upon by two
individual forces (both in a vertical direction); the free-body diagram
for the particular object is shown at the right. During the discussion,
Anna Litical suggests to Noah Formula that the object under
discussion could be moving. In fact, Anna suggests that if friction
and air resistance could be ignored (because of their negligible size),
the object could be moving in a horizontal direction. According to
Anna, an object experiencing forces as described at the right
could be experiencing a horizontal motion as described
below.
Noah Formula objects, arguing that the object could not have any horizontal motion if
there are only vertical forces acting upon it. Noah claims that the object must be at rest,
perhaps on a table or floor. After all, says Noah, an object experiencing a balance of
forces will be at rest. Who do you agree with?
__________________________________________________________
__________________________________________________________
__________________________________________________________
11.
The process of determining the acceleration of an object demands that the mass
and the net force are known. If mass (m) and net force (Fnet) are known, then the
acceleration is determined by use of the equation.
_____________
12.
An applied force of 50 N is used to accelerate an object to the right across a
frictional surface. The object encounters 10 N of friction. Use the diagram to determine
the normal force, the net force, the mass, and the acceleration of the object. (Neglect air
resistance.)
13.
An applied force of 20 N is used to accelerate an object to the right across a
frictional surface. The object encounters 10 N of friction. Use the diagram to determine
the normal force, the net force, the coefficient of friction ("mu") between the object and
the surface, the mass, and the acceleration of the object. (Neglect air resistance.)
14.
A 5-kg object is sliding to the right and encountering a friction force which slows
it down. The coefficient of friction ("mu") between the object and the surface is 0.1.
Determine the force of gravity, the normal force, the force of friction, the net force, and
the acceleration. (Neglect air resistance.)
15.
Free-body diagrams for four situations are shown below. The net force is known
for each situation. However, the magnitudes of a few of the individual forces are not
known. Analyze each situation individually and determine the magnitude of the unknown
forces.
16.
A rightward force is applied to a 6-kg object to move it across a rough surface at
constant velocity. The object encounters 15 N of frictional force. Use the diagram to
determine the gravitational force, normal force, net force, and applied force. (Neglect air
resistance.)
17.
A rightward force is applied to a 10-kg object to move it across a rough surface at
constant velocity. The coefficient of friction between the object and the surface is 0.2.
Use the diagram to determine the gravitational force, normal force, applied force,
frictional force, and net force. (Neglect air resistance.)
18.
A rightward force is applied to a 5-kg object to move it across a rough surface
with a rightward acceleration of 2 m/s/s. The coefficient of friction between the object
and the surface is 0.1. Use the diagram to determine the gravitational force, normal force,
applied force, frictional force, and net force. (Neglect air resistance.)
19.
A rightward force of 25 N is applied to a 4-kg object to move it across a rough
surface with a rightward acceleration of 2.5 m/s/s. Use the diagram to determine the
gravitational force, normal force, frictional force, net force, and the coefficient of friction
between the object and the surface. (Neglect air resistance.)
20.
Go to Free Fall and Air Resistance. Answer the following true or false questions
posed in the first animation. This is without air resistance.
a. The elephant and the feather each have the same force of gravity.
b. The elephant has more mass, yet both elephant and feather experience the same
force of gravity.
c. The elephant experiences a greater force of gravity, yet both the elephant and the
feather have the same mass.
d. On earth, all objects (whether an elephant or a feather) have the same force of
gravity.
e. The elephant weighs more than the feather, yet they each have the same mass.
f. The elephant clearly has more mass than the feather, yet they each weigh the
same.
g. The elephant clearly has more mass than the feather, yet the amount of gravity
(force) is the same for each.
h. The elephant has the greatest acceleration, yet the amount of gravity is the same
for each.
21.
Answer the following true or false questions posed in the second animation. This
is with air resistance.
a. The elephant encounters a smaller force of air resistance than the feather and
therefore falls faster.
b. The elephant has a greater acceleration of gravity than the feather and therefore
falls faster.
c. Both elephant and feather have the same force of gravity, yet the acceleration of
gravity is greatest for the elephant.
d. Both elephant and feather have the same force of gravity, yet the feather
experiences a greater air resistance.
e. Each object experiences the same amount of air resistance, yet the elephant
experiences the greatest force of gravity.
f. Each object experiences the same amount of air resistance, yet the feather
experiences the greatest force of gravity.
g. The feather weighs more than the elephant, and therefore will not accelerate as
rapidly as the elephant.
h. Both elephant and feather weigh the same amount, yet the greater mass of the
feather leads to a smaller acceleration.
i. The elephant experiences less air resistance and than the feather and thus reaches
a larger terminal velocity.
j. The feather experiences more air resistance than the elephant and thus reaches a
smaller terminal velocity.
k. The elephant and the feather encounter the same amount of air resistance, yet the
elephant has a greater terminal velocity.
22.
For each case, use the diagrams to determine the net force and acceleration of the
skydiver at each instant in time. Then use the pop-up menus to view the answers.
23.
Go to the next animation (after the section on terminal velocity).
a.
What is the acceleration of the sky diver when the air resistance equals their
weight? _____________
b.
When the parachute opens, is the upward force ever bigger than the downward
force? ___________
c.
Does the sky diver ever move up? _____________
Physics
Name ___________KEY_____________
Newton’s Second Law
Period _____
Use the following site to answer the questions below.
http://www.glenbrook.k12.il.us/gbssci/phys/Class/newtlaws/n
ewtltoc.html
Lesson Three
1.
Newton’s Second Law States
The acceleration of an object as produced by a net force is directly
proportional to the magnitude of the net force, in the same direction as the
net force, and inversely proportional to the mass of the object.
2.
Newton’s Second Law in a formula is
Fnet = m * a
3.
The units for F are (give an equation showing the
unit and what it is equivalent to.)
4.
Complete the table below
Mass in
kilograms
10
20
20
10
Force in newtons
2
2
4
2
Acceleration
in m/s/s
5
10
5.
Consider the two ticker tape traces below for an acceleration of a car. From the
trace, determine the direction of the net force which is acting upon the car. Show with an
arrow on the diagram the direction of the force.
6.
What acceleration will result when a 12-N net force applied to a 3-kg object? A 6kg object?
________
7.
A net force of 16 N causes a mass to accelerate at a rate of 5 m/s2. Determine the
mass.
____________
8.
An object is accelerating at 2 m/s2. If the net force is tripled and the mass is
doubled, then what is the new acceleration?
_____________
9.
An object is accelerating at 2 m/s2. If the net force is tripled and the mass is
halved, then what is the new acceleration?
_____________
10.
Are You Infected with the Misconception?
Two students are discussing their physics homework prior to class.
They are discussing an object which is being acted upon by two
individual forces (both in a vertical direction); the free-body diagram
for the particular object is shown at the right. During the discussion,
Anna Litical suggests to Noah Formula that the object under
discussion could be moving. In fact, Anna suggests that if friction
and air resistance could be ignored (because of their negligible size),
the object could be moving in a horizontal direction. According to
Anna, an object experiencing forces as described at the right
could be experiencing a horizontal motion as described
below.
Noah Formula objects, arguing that the object could not have any horizontal motion if
there are only vertical forces acting upon it. Noah claims that the object must be at rest,
perhaps on a table or floor. After all, says Noah, an object experiencing a balance of
forces will be at rest. Who do you agree with?
Anna is correct. If the object was in motion to begin with it
will stay in motion.
11.
The process of determining the acceleration of an object demands that the mass
and the net force are known. If mass (m) and net force (Fnet) are known, then the
acceleration is determined by use of the equation.
12.
An applied force of 50 N is used to accelerate an object to the right across a
frictional surface. The object encounters 10 N of friction. Use the diagram to determine
the normal force, the net force, the mass, and the acceleration of the object. (Neglect air
resistance.)
13.
An applied force of 20 N is used to accelerate an object to the right across a
frictional surface. The object encounters 10 N of friction. Use the diagram to determine
the normal force, the net force, the coefficient of friction ("mu") between the object and
the surface, the mass, and the acceleration of the object. (Neglect air resistance.)
14.
A 5-kg object is sliding to the right and encountering a friction force which slows
it down. The coefficient of friction ("mu") between the object and the surface is 0.1.
Determine the force of gravity, the normal force, the force of friction, the net force, and
the acceleration. (Neglect air resistance.)
15.
Free-body diagrams for four situations are shown below. The net force is known
for each situation. However, the magnitudes of a few of the individual forces are not
known. Analyze each situation individually and determine the magnitude of the unknown
forces.
16.
A rightward force is applied to a 6-kg object to move it across a rough surface at
constant velocity. The object encounters 15 N of frictional force. Use the diagram to
determine the gravitational force, normal force, net force, and applied force. (Neglect air
resistance.)
17.
A rightward force is applied to a 10-kg object to move it across a rough surface at
constant velocity. The coefficient of friction between the object and the surface is 0.2.
Use the diagram to determine the gravitational force, normal force, applied force,
frictional force, and net force. (Neglect air resistance.)
18.
A rightward force is applied to a 5-kg object to move it across a rough surface
with a rightward acceleration of 2 m/s/s. The coefficient of friction between the object
and the surface is 0.1. Use the diagram to determine the gravitational force, normal force,
applied force, frictional force, and net force. (Neglect air resistance.)
19.
A rightward force of 25 N is applied to a 4-kg object to move it across a rough
surface with a rightward acceleration of 2.5 m/s/s. Use the diagram to determine the
gravitational force, normal force, frictional force, net force, and the coefficient of friction
between the object and the surface. (Neglect air resistance.)
20.
Go to Free Fall and Air Resistance. Answer the following true or false questions
posed in the first animation. This is without air resistance.
a. The elephant and the feather each have the same force of gravity.
b. The elephant has more mass, yet both elephant and feather experience the same
force of gravity.
c. The elephant experiences a greater force of gravity, yet both the elephant and the
feather have the same mass.
d. On earth, all objects (whether an elephant or a feather) have the same force of
gravity.
e. The elephant weighs more than the feather, yet they each have the same mass.
f. The elephant clearly has more mass than the feather, yet they each weigh the
same.
g. The elephant clearly has more mass than the feather, yet the amount of gravity
(force) is the same for each.
h. The elephant has the greatest acceleration, yet the amount of gravity is the same
for each.
21.
Answer the following true or false questions posed in the second animation. This
is with air resistance.
a. The elephant encounters a smaller force of air resistance than the feather and
therefore falls faster.
b. The elephant has a greater acceleration of gravity than the feather and therefore
falls faster.
c. Both elephant and feather have the same force of gravity, yet the acceleration of
gravity is greatest for the elephant.
d. Both elephant and feather have the same force of gravity, yet the feather
experiences a greater air resistance.
e. Each object experiences the same amount of air resistance, yet the elephant
experiences the greatest force of gravity.
f. Each object experiences the same amount of air resistance, yet the feather
experiences the greatest force of gravity.
g. The feather weighs more than the elephant, and therefore will not accelerate as
rapidly as the elephant.
h. Both elephant and feather weigh the same amount, yet the greater mass of the
feather leads to a smaller acceleration.
i. The elephant experiences less air resistance and than the feather and thus reaches
a larger terminal velocity.
j. The feather experiences more air resistance than the elephant and thus reaches a
smaller terminal velocity.
k. The elephant and the feather encounter the same amount of air resistance, yet the
elephant has a greater terminal velocity.
22.
For each case, use the diagrams to determine the net force and acceleration of the
skydiver at each instant in time. Then use the pop-up menus to view the answers.
23.
Go to the next animation (after the section on terminal velocity).
a.
What is the acceleration of the sky diver when the air resistance equals their
weight? _____________
b.
When the parachute opens, is the upward force ever bigger than the downward
force? ___________
c.
Does the sky diver ever move up? _____________