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Name ___________________________ Class ________ Date ___________
TEKS
IPC
Lesson 4D
TEKS 4D Assess the relationship between force, mass, and acceleration, noting the
relationship is independent of the nature of the force, using equipment such as
dynamic carts, moving toys, vehicles, and falling objects.
TEKS Lesson 4D: Force, Mass,
and Acceleration
What is force?
A force is a push or a pull that acts on an object. A force can cause a resting object to move, or it can
accelerate a moving object by changing the object’s speed or direction or both. Force is measured in
newtons (N). One Newton is the force that causes a 1-kilogram mass to accelerate at a rate of 1 meter per
second each second (m/s2).
Forces can be combined. Forces in the same direction add together. Forces in opposite directions subtract
from one another. The net force is the overall force acting on an object.
What is the relationship between force, mass, and
acceleration?
An unbalanced force causes an object’s velocity to change. In other words, an object accelerates if the net
force on an object is not equal to zero. Force is not the only factor that affects the acceleration of an
object. The acceleration of an object also depends on its mass.
The relationship between force, mass, and acceleration can be summarized by Newton’s second law of
motion. According to Newton’s second law of motion, the acceleration of an object is equal to the net
force acting on it divided by the object’s mass. Newton was able to put these ideas into a single formula.
Acceleration =
or a 
Net force
Mass
F
m
The acceleration of an object is in the same direction as the net force. The formula can be arranged to
show how much force must be applied to an object to get it to accelerate at a certain rate.
Net force = Mass × Acceleration
or F = ma
For example, you apply a net force to a ball when you throw it. The harder you throw, the more the ball
accelerates. If you double the force, the acceleration of the ball doubles as well. Similarly, if you keep the
amount of force constant but throw a ball with half the mass, then the acceleration will double.
The nature of the force, or what causes the force, does not affect the relationship between force, mass, and
acceleration. Only the magnitude of the force and the mass of an object determine the acceleration of the
object. Whether you throw a ball or a machine throws a ball, the ball will have the same acceleration if
you and the machine both exert the same magnitude of force on the ball.
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Name ___________________________ Class ________ Date ___________
TEKS
IPC
Lesson 4D
Lesson Check
1. Identify According to Newton’s second law of motion, acceleration of an object depends upon
the ______________________ of the object and the ______________________ acting on it.
2. Define Is the following sentence true or false? The acceleration of an object is always in the
same direction as the net force acting on the object. ______________________
3. Define Is the following sentence true or false? If the same force acts upon two objects with
different masses, the acceleration will be greater for the object with greater mass. _____________
4. Assess Assess the relationship between force, mass, and acceleration.
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5. Assess Three kids pull a bail of hay across a field. One horse applies the same magnitude of force
as the three kids to pull the bail of hay across a field. Is the acceleration of the hay greater when the
horse applies the force than when the three kids apply the force? Use this example to assess how
the nature of a force affects the relationship between force, mass, and acceleration.
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