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# Projectiles question watch

1. Please look at the image attached

Two small stones are projected horizontallyh towards each other at the same instant over horizontal ground. Initally the stones are 19.6m above the ground and are 50m apart. The intial speeds of the stones are 15 and v.

What is the value of v if the stones collide at 4.9m above the ground?
Attached Images

2. What have you done so far? I got it, but I want to know where I should start.

edit: Hello again
3. (Original post by high_maintenance_girl)
Please look at the image attached

Two small stones are projected horizontallyh towards each other at the same instant over horizontal ground. Initally the stones are 19.6m above the ground and are 50m apart. The intial speeds of the stones are 15 and v.

What is the value of v if the stones collide at 4.9m above the ground?
using

you should know that vertical distance traveld is 19.6 - 4.9 = 14.7 and acceleration due to gravity is 9.8

now you can find t.

from this there are a few ways to work it out

we can use

we know v = 15 and we know t, so we can find the horizontal ditance travel by one stone, now we can use 50 - this answer, to find the ditance traveled by the other stone

and using

4. yes indeed hello there again!
well tbh ive done nothing i tried a couple of things but now i just have papers with scribbles on it lol
erm from a previous part of the question....ive correctly worked out...
that for the left hand stone thingy
the time between projection is 2 seconds
and that the horizontal distance travelled is 30m
that is all

i think i should add you to my buddy list lol
how old are you? and at what level are you studying maths?
5. thanks for the edit chaoslord i was very confused then lol
6. (Original post by high_maintenance_girl)
thanks for the edit chaoslord i was very confused then lol
so have you got it now?

are the questions directed at me?
7. (Original post by Chaoslord)
so have you got it now?

are the questions directed at me?
erm well i got time as root 3 seconds
although im not familar with the s = v x t formula, i used it got the wrong answer

and sorry no the questions were towards d-day - should've quoted
but i was lazy and just did quick post
8. (Original post by high_maintenance_girl)
erm well i got time as root 3 seconds
although im not familar with the s = v x t formula, i used it got the wrong answer

and sorry no the questions were towards d-day - should've quoted
but i was lazy and just did quick post
WOAHHHHHH take that back xD

you ARE familiar with it! xD you probably dont understand the form

it means, distance traveled = speed x time

1 mph, traveling for one hour.

you travel 1 mile xD

the time between projection is 2 seconds
and that the horizontal distance travelled is 30m
that is all
time = 2
v = 15

horizontal distance traveled = 30 which is what you got

this wont work for the vertical component as there is an acceleration due to gravity
9. (Original post by Chaoslord)
WOAHHHHHH take that back xD

you ARE familiar with it! xD you probably dont understand the form

it means, distance traveled = speed x time

LMAO
i am dumb
10. (Original post by high_maintenance_girl)
LMAO
i am dumb

its okay you get it now though right? or would you like me to explain some more?
11. (Original post by Chaoslord)
its okay you get it now though right? or would you like me to explain some more?
12. (Original post by high_maintenance_girl)
Spoiler:
Show

considering the vertical motion

(they were thrown from 19.6m and they meet at 4.9m so the distance traveled is 14.7m

since they fall from rest

this is the acceleration due to gravity

subbing in we get

now consider the horizontal components

for stone 1 (on the left)

and

using

horizontal distance traveled by stone 1 =

so the distance traveled by stone 2 =

using

i get

sorry i kept confusing myself with typos xD
13. thank you very very much
ive screenshotted that and kept it lol
and what typos?
15. (Original post by high_maintenance_girl)
thank you very very much
ive screenshotted that and kept it lol
and what typos?

roffle mao.

accroding to my original calculations 3/2 time 2 = 3/4
16. :>.<:
17. yea just for that i deserved minus rep xD

18. I think so. I deleted it already

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