Download the physics of car accidnets


In the absence of
external forces, an
object at rest
remains at rest and
an object in motion
remains in motion
with a constant
velocity.

Don’t let this be you. Wear seat belts.
Because of inertia, objects (including
you) resist changes in their motion. When
the car going 80 km/hr is stopped by the
brick wall, your body keeps moving at 80
km/hr.
The acceleration of an
object is directly
proportional to the net
force acting on it and
inversely proportional to
its mass or F=ma
 Force is measured in
newtons. One newton is
the force required to
accelerate a 1-kg mass
to 1 m/sec2.

A large vehicle traveling at the
same rate as a smaller vehicle
will have more force due to its
greater mass
So  Ride in the
Bigger Truck

The force exerted by
object 1 onto object 2 is
equal in magnitude and
opposite in direction to
the force exerted by
object 2 onto object 1.
When the bumper car
you are in strikes another
car, it strikes the car you
are riding in with equal
force.
 Great for bumper
cars…not for real cars

Friction is a force that resists motion when
two objects are in contact.
 If you look at the surfaces of all objects,
there are tiny bumps and ridges. Those
microscopic peaks and valleys catch on
one another when two objects are
moving past each other.

The level of friction is measured by the
coefficient of friction.
 The formula is µ = f / N, where µ is the
coefficient of friction, f is the amount of
force that resists motion, and N is the
normal force.



Normal force is the force at which one surface
is being pushed into another. If a rock that
weighs 50 newtons is lying on the ground, then
the normal force is that 50 newtons of force.
The higher µ is, the more force resists motion if
two objects are sliding past each other.
There are two forms of friction, kinetic and
static.
 If you try to slide two objects past each
other, a small amount of force will result in
no motion. The force of friction is greater
than the applied force. This is static friction.
 If you apply a little more force, the object
"breaks free" and slides, although you still
need to apply force to keep the object
sliding. This is kinetic friction. You do not
need to apply quite as much force to keep
the object sliding as you needed to
originally break free of static friction.




In some places, especially Alaska in the winter,
you must keep friction in your mind constantly
as you drive, in order to avoid an accident.
You have to limit your speed in order to be
able to stop at a reasonable distance, and to
negotiate curves.
Braking distance can be calculated using the
equation d = V2 / 2gµ
Where:
d = Braking Distance
g = Acceleration due to gravity (9.80 m/sec2)
V = Initial vehicle speed (m/sec)
µ = Coefficient of friction between the tires and
the roadway
Causes you to experience a slightly
different set of forces, as you must deal
with the tendency for a car to want to
travel straight ahead.
 This is explained by Newton's 1st law: an
object will not change velocity without a
force acting on it.


In this case, you are causing
the car to change lateral
velocity and move to the side
by applying frictional force
from the tires. If the tires don't
have a coefficient of friction
large enough to provide the
force needed to move the
car laterally, then you slide
straight forward and off the
road.