SIJI K.SPHYSICAL

SCIENCE

An object at rest tends to stay at rest and an object in motion tends to stay in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

What

does that

means?

An object in motion wants to stay in

motion, and an object at rest wants to stay

at rest.

This is also called INERTIA

The car is at rest, and it is going to stay at rest

until a force gives it a push.

Now that is moving, it will continue to move until another force stops it.

Friction

The best place to test inertia is in Space, why?

In outer space there is no air, or anything else to create friction. So moving objects will keep moving forever, and objects that aren't moving will stand still forever.

•The crash dummy is not wearing a seat belt and is moving along with the car.

•Both the car and the dummy are moving at, say 60 mph. 

•When the car hits the cement road divider, it is stopped (an outside force stops it from moving). 

•The crash dummy, however is not so lucky.  Since he is not wearing a seat belt and is not connected to the car, he will continue to move at 60 mph.  This means he will go flying out through the front windshield.

•The dummy will fly through the air until he hits the ground. 

•This is because the earth's gravity stopped him from moving any further. 

•If this collision had happened in zero-gravity, in a vacuum, the dummy would theoretically keep on hurtling away from the car at 60 mph.