why did you put a = -9.81 for part B and C, Should it not be a = 9.81, as now arrow moves down. i e. direction of gravity.
@sebastienfossati-sharples126
3 жыл бұрын
Great help, thank you
@Mirsab
5 жыл бұрын
This better be for 20 marks! 😂
@venmis137
3 жыл бұрын
Nah, it'll be 3 marks max.
@harrynathan9698
3 жыл бұрын
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@jonathanmiller5621
3 жыл бұрын
@Harry Nathan instablaster ;)
@harrynathan9698
3 жыл бұрын
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3 жыл бұрын
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@mypreciouspatpran
3 жыл бұрын
How is the initial velocity same for horizontal and vertical component? Shouldn't the vertical initial velocity be found by 100sin45
@worstbuffs9189
3 жыл бұрын
I was thinking the same thing. In the previous video, which practically uses the same principles, he did use sin for the vertical component of velocity.
@worstbuffs9189
3 жыл бұрын
In fact 100cos(45) and 100sin(45) are the same value.
@rishi5142
3 жыл бұрын
@@worstbuffs9189 its the question, usually they arent the same
@theemilya7732
4 жыл бұрын
Hi why is 'a' negative for all three sections, when in section A it is travelling upwards. You defined upwards as positive, yes, so it makes sense that a = -9.81 as gravity is acting down...BUT in section B and C the arrow is now heading towards the ground so surely a is now positive...please could you explain?
@ishanr8697
2 жыл бұрын
Whichever direction you choose as the positive direction, you keep it the same. Acceleration's direction isn't defined in terms of the velocity's direction, but with respect to your coordinate system.
@edwardhudson815
Жыл бұрын
@@ishanr8697 Surely not because the results of each part only make sense when you use a = -9.81 throughout, else for example v=u+at where v = 0 and u = 70.71, trying to find t, the object is travelling upwards, using a positive a would give a negative time
@myoldfriend4810
4 жыл бұрын
Why is the acceleration upwards negative in all the three sectors and where did u get that height of 100m for section C????
@edwinr7689
3 жыл бұрын
@Michael Gardner safe g
@rizanrishwan7794
3 жыл бұрын
@Michael Gardner another late reply but acceleration due to gravity will always act downwards and in this case since he took upwards as positive, downward acceleration at all the sections will be negative
@finleyjohnson4193
2 жыл бұрын
thankyou. this was super helpful
@maulanaakbar7510
10 ай бұрын
Hi i love your videos. You did a very goodjob in explaining the topic than my teacher. The only thing im confuse is why have you concluded that displacement c is -100m?
@pahcreates378
9 ай бұрын
Since displacement is a vector, we can measure its change (Delta) by doing: (during flight in part C) Final distance (ground level) - Initial distance (In air) 0m - 100m = -100m
@maulanaakbar7510
8 ай бұрын
@@pahcreates378 ahhh i see that makes sense thank you for the help and sorry for the late reply 🙏🙏🙏
@pahcreates378
8 ай бұрын
@@maulanaakbar7510 npp 😉
@georgemathew8218
4 жыл бұрын
lets us look at this convention.. Acceleration due to gravity is positive if both force (gravity here) and displacement are in same direction. g = + 9.8m/s2 when a body is dropped. Example A body is dropped means initial velocity is zero. Imagine body takes 3 seconds to reach the ground. g = + 9.8m/s2 meant that after 1sec the speed becomes 9.8m/s, after two seconds it becomes 19.6m/s and after 3 seconds it becomes 29.4m/s. It means that it strikes the ground with a velocity of 29.4m/s. g = + 9.8m/s2, positive sign meant that the body increases it speed by 9.8m/s for every one second. Lets look at it in the reverse manner when you throw a body with a speed of 29.4m/s, it becomes 19.6m/s after one second, 9.8m/s after 2 seconds and zero after 3 seconds at its maximum height. Here g = -9.8m/s2 negative sign indicates the speed is decreasing
@bengarner2659
Жыл бұрын
Wouldn’t the initial vertical be equal to u sin feta rather than it being the horizontal velocity
@FlixRacing
3 ай бұрын
THANK YOU!
@Mirsab
5 жыл бұрын
6:17 Shouldn't the a=9.81 instead of - 9.81 cos this time it's actually moving in direction of gravity?
@lukesargent9413
5 жыл бұрын
No because +ve is upwards and it should stay negative if -ve is downwards
@SabrinaXe
4 жыл бұрын
Doesn't matter whether the object is aligned in the direction of gravity. Gravity always acts downwards, it pulls you towards the earth no matter what part of earth your at
@archiebrew8184
4 жыл бұрын
Bruh imagine if time was vector
@tavrisscott
2 жыл бұрын
@@archiebrew8184 hahaha that would be crazy
@FlixRacing
3 ай бұрын
Good luck everyone!
@mohammadbilal7206
6 жыл бұрын
What effects would air resistance have on the horizontal component or even on the vertical component?
@mihirshah3332
Жыл бұрын
Horizontal velocity would reduce due to air resistance, and the acceleration downwards would be slower too.
@mariamalkoragaty1974
4 жыл бұрын
Hello Sir. Just wanted to ask why is s = -100m in part C, the only ''100 value'' I understand is the launched velocity at 100 ms-1 which was given. Please can anyone help me on this? Thanks :-)
@mariamalkoragaty1974
4 жыл бұрын
oh nevermind I realised that was a given value by him at 6:24. It makes sense now.
@maryammaher167
Жыл бұрын
I had the same question. But the value shouldve been written from the beggining as the height of the cliff
@iybeo4041
Жыл бұрын
at 6:08 why is the acceleration at B still negative 9.81 shouldnt it be positive since its going downwards??
@zhar9177
5 ай бұрын
NO our convention was +ve upwards
@georgemathew8218
4 жыл бұрын
SUPERB EXPLAINATION SIr. @
@RagingLoner13
2 жыл бұрын
now how would you perhaps find the angle at the time of landing?
@rosep4424
5 жыл бұрын
Where has the -100m come from on part C? I don't understand as there is no distances labeled on the diagram. Thank you
@lukesargent9413
5 жыл бұрын
he must have just made it up as a displacement valcue to use
@eyiramcofie2504
3 жыл бұрын
He stated at the beginning of the video that the cliff is 100 m high
@revising-lx2or
8 ай бұрын
thanks@@eyiramcofie2504
@hritiksehgal8126
6 жыл бұрын
7.58 sir how did you get -83.44. When I did -70.71^2x2(-9.81)x-100 I got -3038. Square root wouldn't work because its a minus number.
@PhysicsOnline
6 жыл бұрын
Check your working again. -70.71 squared is 5000. 2 x -9.81 x -100 = 1962. So v squared is equal to +6962. V = 83.44
@Suraj-so3ge
5 жыл бұрын
Why can’t you use S=ut + 1/2at^2
@Suraj-so3ge
5 жыл бұрын
Is it because it forms quadratic and that’s not allowed in Physics ( I do mechanics in A level maths and so we use this equation & S= vt- 1/2at^2)
@ishanr8697
2 жыл бұрын
@@Suraj-so3ge This is possible, you will need to solve the quadratic and pick the relevant root.
@liamcollins7885
Жыл бұрын
legend
@zahrafauzilazim6631
2 жыл бұрын
a bit late to ask a question but can I also find the total displacement by finding the displacement of each part and adding up? or would that not make sense coz you would have to do horizontal and vertical components separately?
@kujojotaro3035
2 жыл бұрын
yeah i still dont get it
@kujojotaro3035
2 жыл бұрын
because like for your final answer of total displacement, the time is just for part C? so like shoudlnt you add it all together?
@kujojotaro3035
2 жыл бұрын
oh wait no, he adds all the time together so it would make sense
@stephenabraham2448
2 жыл бұрын
@@kujojotaro3035 yeah i think all you need to do is add the displacements for the horizontal if you want the total horizontal displace ment aka range and for total vertical displacement i think its 0 since it hits the ground but im not sure. the only reason he adds time up is because its the same for both
@kujojotaro3035
2 жыл бұрын
@@stephenabraham2448 wait when?
@user-kp9zd3xd4z
9 ай бұрын
how did the displacement become -100 i didnt understand that part please
@revising-lx2or
8 ай бұрын
apparently he said the the height of the cliff was 100m at the start of the video in which it's negative because it's moving down
@vishanidesilva1713
Жыл бұрын
hi,how did S become 100m?
@aimeeliu2825
4 жыл бұрын
I was just wondering why is the time for vertical and horizontal components always the same?
@ethangoldwyre
4 жыл бұрын
the time in this is how long the arrow is in the air for, since time isn't a measurement of distance or speed, they don't affect it
@doingnothing3712
6 жыл бұрын
3:24 but isnt u= 100sin45= 85.09??
@PhysicsOnline
6 жыл бұрын
Aeroplanes Lover No it isn’t. Because it is at 45 degrees you have the same component of velocity in the vertical and horizontal directions. Cos 45 = sin 45.
@doingnothing3712
6 жыл бұрын
A Level Physics Online oh sorry my calculator was on radians mode. Thanks a lot for videos. I understand physics more as I watch more of your videos.
@PhysicsOnline
6 жыл бұрын
Aeroplanes Lover Not a problem- a common mistake to make.
@angelo6082
5 жыл бұрын
is the vertical displacement at the end of B zero?
@lukesargent9413
5 жыл бұрын
i would say yes
@eyiramcofie2504
3 жыл бұрын
Yes because from the start of A to the end of B the displacement would be a straight horizontal line so there would be no vertical displacement so 0
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