Learning Goal:
To understand Newton's 1st law
Newton's Principia states this first law of motion:
An object subject to no net force maintains its state of
motion, either at rest or at constant speed in a right line.
This law may be restated as follows: If the sum of all
forces acting on an object is zero, then the acceleration
of that object is zero. Mathematically this is just a special
case of the 2nd law of motion, $\sum \vec{F} = m\vec{a}$, when
$\sum \vec{F} = 0$. When studying Newtonian mechanics, it is best
to remember the 1st law in two ways:
1. If the net force (i.e., sum of all forces) acting
on an object is zero, the object will keep
moving with constant velocity (which may
be zero).
2. If an object is moving with constant velocity,
that is, with zero acceleration, then the net
force acting on that object must be zero.
Complete the following sentences to see if you can apply these ideas.
Part A
If a car is moving to the left with constant velocity, one can conclude that
O there must be no forces applied to the car.
O the net force applied to the car is directed to the left.
O the net force applied to the car is zero.
O there is exactly one force applied to the car.
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Part B
DELL
69°F