Why, when you throw a tennis ball up in the front of a moving car, doesnt it land up in the back seat?

Question

if you throw the ball up outside of the car, it falls where you dropped it and so you pass it, but if you throw it up inside the car it actually travels forward with you! how is that? please answer in words that i can understand if possible : )

Answer 1

Simple.  Because you and it are traveling as fast as the car is traveling when you throw it up.  Therefore, it travels as far as the car travels during the time it is in the air.  

Answer 2

It's called inertia. When you toss the ball up in the car, it is already moving along at the same speed as the car, you and your hand. So when you release it, all you see is the up and down motion, but an observer outside the car would see it go up and forward a long way while it was in the air.

Answer 3

The tennis ball is travelling at the same speed as the car. If you aimed towrds the front seat of a passing car, assuming the timing was correct, it would land in the back seat. It is NOT moving at the same speed as the car in that same direction. Whu?

Answer 4

It is called an inertial reference frame. When you throw it outside both you and the ball are going the same speed, 0 mph, so when it goes up it just goes straight above you hand and comes back down.

When you are in a car that is at a constant speed both you and the ball are going the same speed, say 30 mph, this is exactly the same as the above case when you are going 0 mph. Since both you and the ball are going the same speed and NOT accelerating the ball will always go straight up and straight down. This is true in any inertial reference frame.

If the car was accelerating then it changes things. If you throw the ball when the car accelerating the ball would land in the back seat. This is because when you threw the ball it was at say 20 mph, however since the ball was only going 20 mph and you and the car were accelerating when the ball is in the air you get up to a speed of 25 mph. So now you are going faster then the ball. This is equivalent to throwing a ball and then walking forwards. The ball was stationary with respect to the ground when you threw it but now you are traveling with respect to the ground, and therefore traveling with respect to the ball, so it will land behind you.

That was pretty long but hopefully it made sense.

Answer 5

Newton's laws of motion!   The one in question is that a body in motion tends to remain in motion unless acted on by an outside force.  

The ball is in forward motion inside the car, with the car.  So it keeps pace with the car.  So do you, you don't feel the car pushing you along, right?   Now, if it was a convertible and the ball got up into the still air above, that air would act to slow it down and it would fall behind.  If the car suddenly braked, it would keep moving and hit the windshield.  

This is what is called a frame of reference.  With everything moving along at one speed, you can't tell that it isn't all just standing still.  Everything in the car IS still with respect to everything else in the car.