Download 6.2 Newton`s Second Law

6.2 Newton's Second Law
pp. 142-146
NEWTON’S SECOND LAW OF
MOTION

The acceleration of an object
depends on the mass of the object
and the amount of force applied to it.
NEWTON’S SECOND LAW OF
MOTION

In other words…
 Force causes an object to
accelerate, while the object’s mass
resists the acceleration.
 The larger the object (the more
mass it has), the harder it is to
accelerate.
6.2 The newton


The S.I. unit of
force (newton) is
defined by the
second law.
A newton is the
amount of force
needed to
accelerate a 1 kg
object by 1m/s/s.
Measuring Force

There are 2 units that are commonly used
to measure force:

Pounds
Newtons

1Newton = 1 kilogram • m/sec2

1pound = 4.448 Newtons


1 Newton isn't a very big force: it's about
the weight of an apple
6.2 Newton’s second law

1.
2.
3.
There are three main ideas related to
Newton’s Second Law:
Acceleration is the result of unbalanced
forces.
A larger force makes a proportionally
larger acceleration.
Acceleration is inversely proportional to
mass.
6.2 Newton’s second law

Unbalanced forces cause changes in
speed, direction, or both.
6.2 Acceleration, force and mass

The acceleration caused by a force is
proportional to force and inversely
proportional to mass.
6.2 Applying the second law

Keep the following important
ideas in mind:
1. The net force is what causes
acceleration.
2. If there is no acceleration, the
net force must be zero.
3. If there is acceleration, there
must also be a net force.
4. The force unit of newtons is
based on kilograms, meters,
and seconds.