A worker stands on top of a moving car and throws away a heavy ball straight up...?

Question

Ignoring air resistance, do you think the ball will land on the car or behind it?

kindly explain..

thank you for answering

have a nice day

Answer 1

Depends on how straight he tosses it.  If we accept that he tosses it straight up, and that it is heavy enough to overcome what wind resistance there is, it'll come down right on top of him.

Answer 2

i hope u must have indicated the velocity of the car and the weight of the ball for at least we can compute somehow how much force you need to apply on it to achieve a certain velocity. if the car is really fast, i think it won't hit the back end of the car but if the ball is heavy enough that the worker cannot put up a great velocity on it, it would absolutely hit it, no doubt about it

Answer 3

Hahaha shaun H got owned. Lenky is right, you should give her the 10 points. when you throw the ball up, the ball doesnt go 'up', instead when it goes upwards, it will also slightly shift toward the direction your going. velocity does not matter in this scenario. i cant rmb what caused it... hmm i gotta go find out why too, but anyway im very sure my ans and lenky's are both right.  

Answer 4

If the worker throws the ball exactly vertically then it will land on the car (or on the worker ;) ). The reason is that even though the car is moving, the worker holding the ball is stationary relative to the car and so any action imparted to the ball is equally relative to the worker.

You can demonstrate this very easily for yourself on any moving platform you are on, like a bus or train for example. If you're sitting on a bus and you throw an object straight up, you can catch it as it falls, exactly as if you were sitting on a chair in your living room.

EDIT to add: Sorry ShaunH but what you say is not correct. Consider the situation inside a passenger jet that is flying at about 600 mph. If Someone drops an object, it doesn't go flying off out through the rear of the plane at 600 mph. It lands on the floor or as in my case when my neighbour spilled her coffee, it landed in my lap. I would rather in that case that physics had dictated otherwise, but everything within that aircraft is moving with the same forces acting upon them. Ditto the worker on the car who's holding a ball and then throws it. If viewed by a stationary observer as the car goes past,  the ball describes a parabola as it rises in the air and then falls, but relative to the worker on the car,it goes straight up and down and can be caught.

Try this to prove it for yourself: just jog along at a steady speed (just for a few feet will do) and throw a small object straight up with one hand. A pack of gum, a pen, whatever. Does the object disappear off behind you? No, it doesn't. Relative to your forward movement, it comes straight down and you can catch it -- in front of you.

Gee I hope that's clear... BTW the velocity is irrelevant, because the worker, car and ball are all travelling in the same direction to start with, at the same velocity.

Extra Edit: Apologies Shaun but I have to disagree with your statement:

"Technically this is ignoring air resistance because the ball never has a component of velocity parallel to the velocity vector of the car."

Actually the ball does have a component of velocity parallel to the velocity vector of the car, because the worker was holding it before throwing it. In addition, as air resistance is to be disregarded, it makes no difference whether the worker is inside the car or on top of it. The worker, ball and car are all moving in the same direction prior to the ball being thrown and so the ball's trajectory, relative to the worker, is vertical. Its trajectory relative to a stationary external observer would be parabolic, but as the car is still moving in the same horizontal direction and velocity as the ball and worker had when the ball was thrown, the ball lands on the car and not behind it. Try some practical experiments and you will see that this is correct.

Answer 5

The only force acting on the ball just before it's released is the force directly upwards, so the ball will move directly above the car the instant it was released. Then, the car moves past the point where the ball was released, so the ball lands behind the car. Hope that helps.

EDIT: Reply to Lenky

The person is standing ON TOP of the car, not inside it. The molecules inside the car are stationary relative to the person inside the car, so when the ball is thrown upwards inside the car, you are correct and the ball lands on top of the person.

When he opens the sunroof and throws the ball up through it, the car and the person are moving relative to the air molecules, so the situation is similar to throwing up a ball and then running off. At the point of release, there is only one force acting up on the ball, so the ball moves upward perpendicular to the velocity vector of the car, so the ball lands behind the car. Technically this is ignoring air resistance because the ball never has a component of velocity parallel to the velocity vector of the car.