Question

A student throws a heavy red ball horizontally from a balcony of a tall building with an initial speed v0. At the same time, a second student drops a lighter blue ball from the same balcony. Which ball hits the ground first?

Answer 1

(A) The blue ball reaches the ground first.
(B) The balls reach the ground at the same instant.
(C) The red ball reaches the ground first.
(D) Both balls hit the ground with the same speed.
(E) None of the above statements is true.
whichof them is true

Answer 2

probably the most famous example of motion. Haven't you ever seen this demo?

Answer 3

well h think that only c is true because the red one has an initial speed so it will reach first

Answer 4

is the initial speed in the horizontal direction?

Answer 5

OK - there are a load of misconceptions flying here:

@khaleddx - the initial velocity of the red ball is HORIZONTAL and therefore is not relevant to the vertical motion

The question clearly states 'heavy' and 'light', but does NOT state that air resistance is to be ignored.

@JFraser - the 'famous example' only applies in the absence of air resistance.

Answer 6

projectile and vertical motion questions are taken with neglected air resistance in schools

Answer 7

We do not know the SIZE of the balls - maybe the heavy one is huge and has large air resistance, or maybe they both are the same size but made of different materials.

If they are the same size but one is heavier then the heavier one will in real life, hit the ground first, because the drag force will be th esame on the 2 balls , but the weight of the denser one is more.

IF we are to ignore air resistance then they both hit the ground at the same time and with the same speed....

Answer 8

well the ball was thrown horizontally so i think that the initial speed is horizontally directed

Answer 9

look i think that the problem in the speed not in the weigh

Answer 10

@MrNood yes, but if it's a ball we're talking about, for all practical purposes it's an ideal case

Answer 11

^^ I am wrong above

They hit the ground at the same time, but he red ball has a horizontal component to its velovity as well as a vertical - so its speed is higher than the blue one

Answer 12

they will hit with the same vertical component of speed, but the overall velocities will not be equal

Answer 13

so which answer is the best one

Answer 14

@MrNood has already given you the answer

Answer 15

Yeah - sorry - I do not normally give direct answers (and often take issue with people who do) but in this case tthere was sufficient discussion and the answer seems to be evident.

I think @khaleddx has not truly understood the concept though. - maybe some more reading on this subject would help?

Answer 16

i think y mean that both of them will have the same velocity but not the same speed . and so they will reach the ground at the same moment right?

Answer 17

no they don't have the same velocity or speed

(btw it is not possible to have the same velocity and different speed - but it is possible to have same speed but different velocity)

They both have same vertical speed, but the red one has horizontal speed too.

Answer 18

ok thx i understood now