On the highway of life, do you want to be the

bug or the windshield?

Bug hits windshieldAre the forces equal?

Bug hits windshield

The force on each is…The same - Newton’s third law. You can only exert back as much force as is exerted on you.

If the bug hits the car with 4 oz. of force, the car can only apply 4 oz. of force back.

Is the bug’s velocity changed…Yes - It would be impossible for the bug to hit the windshield for ½ second while the windshield hits the bug for ¾ second, so the same force is applied by the bug back on the windshield for as long a time.

The change of velocity on each is…

Very Different – The car, hardly noticeable. The bug very noticeable. The bug slows down, stops and reverses direction

Think about it…

• What about a BIGGER BUG?

The force on each is…Again, the same Newton’s third law You can only exert back as much force as is exerted on you

But the bug pushes harder nowNewton’s third law You can only exert back as much force as is exerted on you

The change of velocity on each is…

Slightly Different – The car, slows down noticeably. On-the-other-hand, the bug slows down, stops and reverses direction

Back to small bug• So why does the (small) bug go splat, but

a windshield doesn’t?• What’s different?

• The bug has much less mass and hence much less inertia.

It’s only a Small force

when a bug hits the

windshield.

It only takes a small force to kill a bug. That

same tiny force won’t hurt the windshield, and also does little to change the velocity of

the car.

The difference: the

size of the force.

The smaller the bug, the less the forces; the

bigger the bug the greater the action

and reaction forces.

What if the bug was the same mass and same speed as a car?

They stop

The momentum is the same

for each