Free Fall Problems
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- čas přidán 1. 10. 2021
- Physics ninja looks at 3 different free fall problems. We calculate the time to hit the ground, the velocity just before hitting the ground. We apply the kinematic equations to look at free fall when you throw an object straight up or down.
A) Drop Ball = 3:56
B) Throw Ball Up = 10:04
C) Throw Ball Down = 20:11
Thanks Ben Affleck. Highly appreciate it!
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@@kylemcmanus1712Kyle Kyle Kyle
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Incredible! Thank you so much for emphasising on the sign convention.
I wish I can give u a hug irl. These videos are SOOO HELPFUL. STEP BY STEP. YOU didn't skip a single step, matter of fact you showed us multiple ways to do it with diff formulas. You're an absolute GOAT. Thank you! truly an inspiration
Such a nice comment. Thanks for the support.
I really took the advantage of your lecture. I studied kinematic in 1995. But your lecture retained them quickly to my memory.
On FREE FALL This is the best video ever which I didn't found anywhere on whole YT ...I am so glad I found it and now my free fall concept is crystal clear.......Thank you so much sir !!
Well explained, brief and clear.
Thank you so much. The explanation is amazing!
thank you very much sir,you made me understand free fall, keep it up and may God bless you
You explain the concept clearly and beautifully! I subscribed to your channel!
Thanks for the comment. I greatly appreciate your support.
Absolutely! My kids are studying online and this video presents the concept in the clearest way. Thank you. Subscribed
Very clear and easy to understand thank you very much sir
When you are trying to find the max speed before hitting the ground you can also you 0 as your initial velocity and 8.84 as your total displacement to get the same answer
Thank you so much!
Thank you so much for this.
Thank you for this good explanation you explained it even better than my teacher! *tips hat*
Not only did you explain the thing I was stuck on for ages but your teaching style is AWESOME. I wish I had a teacher like you!!!!!!!!! Yeeeeeehaaaaaaaaaa3wwwwwwwwwwwww
This video helps me a lot. Thanks bro
Clearly explained thanks
Use the formula a = Δ
Q. When the ice block was at point Y, the rope slipped through the caterer’s hands, and the block fell. The acceleration of the block toward the ground was 9.8 m/s2. What was the velocity of the block after 0.2 seconds? _______ m/s
Dude, you just saved my freaking life 🎉🎉 keep going
Never have I ever seen such an ad infested video
I haven’t encountered any ad so far tho
A). A stone is thrown straight with a speed of 24m/s. It is caught on its way down at a point 7.2m
above the position it was thrown. How fast was it going when it was caught?
Can you do that examples to me please...
Q1.A ball is thrown upwards with an initial speed of 20 ms-1.
a) how far does the ball rise in 1s?
b)how long does it take to reach the highest point of its motion?
c)what is the maximum height reached by the ball?
Q2.An object falls vertically from the edge of a building and strikes the ground 40 m below.
a)calculate the velocity of the object as it strikes the ground.
b)how long did it take the object to fall 40 m?
c)what is the velocity of the object half way down?
Q3.A golf ball is thrown vertically upwards with initial velocity of 25 m/s and returns to the thrower in 5 s.
a)what is the velocity of the ball at the highest point?
b)how long did it take to reach the highest point?
c)what is the highest point reached by the by?
d)calculate the total distance traveled by the ball.
e)what is the total displacement of the ball?
f)draw a velocity - time graph representing the motion of the ball over the 5 s, showing the following:
1.initial velocity
2.final velocity
3.time to reach the top
4.section representing upwards motion
5.section representing downward motion... please !!!
in part 20:06 why did you not add the time to get up to the max height as well ? How does using 7 meters in the equation give you the total flight time ?
Please use this example
While sitting on a tree branch 10.0m above the ground you drop a ball.
When the ball has fallen 2.5m, you throw a second ball straight down. What initial speed must give the second ball if they are botb to reach the ground at the same time?
Great Video clear. Thank you very much. I got this question, kindly help me.
A ball is dropped from rest a height h above the ground at the instant the first ball is released. Determine the velocity of the second ball, if the two meet at h/2 above the ground.
Thanks for the great explanation, my only question isn't Vf for the last problem suppose to be negative because it is going downward?
Yes it should be negative
What if, say, a ball is thrown vertically up, reaches its peak, then falls back down to 20m above its original position?
How should I approach this problem? Should I divide the problem in two? Or is there a one equation solution?
Question, how did you get the 2×7 in the first problem I mean I get where you got the 7 from but not the 2.
Thank you so much
on the second problem when you are finding the speed before hitting the ground should the intial velocity not be 0m/s and the height be 8.84 meters. As the ball would speed up a lot more from a height of 8.84 meters rather than 7 meters.
For the first one your answer is right but working is very in accurate,you teach like a math teacher than a actual physics teacher
Inaccurate
Thank you so much :)
So if the initial velocity is not given when u are throwing the ball down, would u solve like u are dropping the ball down and then add the 1/2(a)(t^2)?
Great explanation, definitely subscribing
Thank you
So, for the final answer, since upwards is positive, it's either 14.2 down or -14.2 right? I'm a bit confused because you canceled out the positive value but still took the positive value. Otherwise, great video though. Thanks for the help!
Edit: Also in B3 shouldn't it just be the magnitude since it's asking for the speed?
good point... i forgot to write the negative sign... the final velocity is negative since i picked up to be positive.
@@PhysicsNinja Thanks for the prompt reply. I appreciate it!
Thanks!, Hope your successful
If you know the initial velocity is 15m/s and the height is 21m and the angle is 40 degrees is there anyway to solve it without using the quadratic equation.
On the second question when finding the total time of the flight why are we using negative 7 instead of the 13. Which we found as the total displacement
How do you find the range for part B. Throwing ball up?
For question B, why don't we use the max height of the ball? I calculated the velocity that way and also got -13.6. Is it just a coincidence or is there only one height we should be using.
first time watching and its like zachary levi is explaining physics pretty cool
For the total flight time, couldn't you have just added added the time for the throw, calculated the time of the fall, and added those together?
I have a question, my teacher told me that in his case, when the object drops down it's a positive value but when it goes up it's a negative value, so does acceleration due to gravity depend on the sign convention we wish to follow?
If you set down to negative, g is -9.8. If you set down to positive g is 9.8
@@jaysan3004 noob
No in both cases gravity will be -9.8 only
Listen take g =9.8 only all your problems will be solved easily with accurate answers
THANK YOU
Thank you so muchhhh!!!
On the last question why did you use -8 velocity for the first equation then +8 for the other equation
if someone dropped an object off a cliff how far would it travel in 8 seconds and how fast would it be traveling at the point of impact. I really would like to know. Thank you. : - )
ur the best physics teacher in youtube.your video helped me a lot
Thank you so much!
This video helped a lot but I do not get the 'negative-Down and positive-Up' stuff.
Is the object still in free fall when it is thrown down?
why did you use 7m instead of 8.84?
Thank you
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Hello! I have a tiny doubt. At 15:47, you mentioned that the change in displacement for y would be -7. Why shouldn't it be 8.84; i.e the calculated height? Because the ball is dropping from that maximum height - or would that be considered the distance rather than the displacement? Thanks!
Distance is a scalar, it’s always positive, displace t is a vector, can be positive or negative, the sign depends on the direction.
Super cool presentation and so helpful keep it up well done.
Thanks so much!
i have a question, for the first number, where did you get 2.7?
I hope you can answer in time but why in B) around 15:14, wouldn’t initial velocity be 0 as we’re finding the speed before it hits ground? Knowing that as it falls the velocity should be 0 as it de-accelerates
That’s what I got confused about as well, and wouldn’t displacement be the (-)8.84?
@@AmmoBops you know final velocity should
Total flight time includes it being thrown up and then going down, why didn't you use 8.84m for delta y. Why only 7, do you forget the time it took to reach the top and then fall??? Flight time is how long was it in the air, it being thrown up should still be included in flight time... Makes no sense
confused about this too
where do u get 2 times 7 over 9.8 on the first one
Why when u calculate total flight time not using the time u found in a highest point/the time the ball was first thrown down
at 11:42 why you didnt use initial velocity on the Y direction Vsinx ? you used the Vinitial 6
At drop ball first problem while solving by yourself, Please take note It is not 0.7 but 0-7 therefore after solving 14 will come not 2.7. at 7:32
alot of free fall questions ask for the velocity of an object WHEN it hits the ground, which is different from just BEFORE hitting the ground. Im just confused on weather those are interchangable or not. does the velocity when the ball hits the ground equal 0?
Also alot of free fall problems ask for the velocity when a person CATCHES the ball. Does that also mean the velocity is equal to 0?
Thank you for such a helpful video by the way! :)
They are the same. The instant it touches the ground it’s no longer in free fall, Ana acceleration will be different.
1) In the second task (can we find
the displacement of the ball in the air of the y axis - trajectory of the ball in the whole movement?)
2) Also can we find the displacement of the x axis (how far the ball landed from the starting position?);
3) Can we separate the different segments deltaYAB and deltaYBC and calculate the paths, which the ball spent in the air?
I hope you can give me a hint.
Yes you can separate
I was trying to figure it out and i solve the problem with math. Kinda not easy task, but hoping you can guide me or give me some tips
Wow men I totally understand the use example in this explanation! You nailed it men
thanks! have a great day
Respectful sir thankyou for this video ..... I was struggling in this cocept for my neet 2024 . Now I've got a real good clarity ❤
You are most welcome! Good luck
Let’s say you only have the seconds it takes for the object to fall to the ground from a cliff. Let’s say a stone takes 12 seconds to fall from the top of a cliff, what’s the height of the cliff?
in your formula you derived has a negative g because you said that objects in free fall goes to the negative y-axis, but why did you use that formula in getting the displacement of the ball thrown upward to the positive y-axis, i think the answer should be d=5.48m not 1.83m
Thanks alots sir for your neat presentation,, however i have got doubt why did you initially consider "g"= -g? May you explain for me
When an object is thrown upward, it's velocity is decreasing until it reaches it's maximum height.
On the contrary, when the object falls back down, it's velocity is increasing until it hits the solid ground. In knowing this, just trust the mathematics and the following basic equation:
Acceleration = (Final velocity - Initial Velocity ) /
Time
Remember that acceleration is equal to the change in velocity over time. Therefore as the object is thrown upward, the velocity is decreasing, so AV would be negative, thus making the acceleration negative.
In free fall, acceleration is also negative because of its downward direction.
You can also see it by drawing a graph.
thank you so much it really helped
Plz apploded full kinematics concept
Should g be positive wen ball is dropping because it's gravity and be negative wen the ball is thrown or Is rising because it's going against gravity
how do i identify if its velocity, velocity initial, speed, displacement and all the other ways to classify them?
Brian Berg of Iowa built a house of cards 4.88 m
tall. Suppose Berg throws a ball from ground level
with a velocity of 9.98 m/s straight up. What is the
velocity of the ball as it first passes the top of the
card house? i need help with this :(
alright bro youre the goat
I have a question how did you get 2 times 7 or 2•7 in problem A?
probably late but basiclly he did simple algebra.
0-7=1/2
0-7=-7
-7 is techniclly -7/1
-7/1=1/2
so he added +7 to both sides
-7=1/2
+7,+7
7 cancels out so it equals to zero
7/1+1/2
and u times 2 by both sides to get the common denomenator
if u didnt understand my bad explanation search up algebra 1 fraction with whole number variable problems
From the roof of a building of 30m height, a stone is vertically thrown upward with an
initial speed of (10m/s), in the vertical frame
OZ
downward oriented. Determine :
1 The speed v of the stone when it reaches the ground
2 The total duration t of the freely falling motion.
Are my answers correct?
1) vf = -26,22 m/s^2
2) t = 4,86 s
7:28 What do you mean by "two at the top?"
May I ask, how did you get that square root of 2.7. I'm hoping for your response because I am confused. Thank you.
Calculator 🙂
it was 2 times 7 not 2.7
For (A), I realized that if a 80kg drunk dude walked off a 7m ledge, he will still take 1.2s to hit the ground at 11.7m/s(43km/hr or 26.7mph), even though his weight(or should i say mass) is many times heavier than the ball. From the equation, the mass of the object is irrelevant.
Then I imagine the same drunk dude walking off the top of Empire State Building at 381m to his death. He will take 8.8s to hit the ground at 86.4m/s(311km/hr or 193.3mph). I want to know the force just before impact so I tried to apply F=ma= 80(9.8)=784N but the value seems to be too small for a falling human being becoming pizza on the ground. In fact 784N seems to be just the weight of the dude standing on the ground due to Earth's gravity. Where did I calculate wrongly?
When an object is dropped from above gravity is positive...Why you using negative g?
But why is time negative? Isn't it positive?
Shouldn't the vf in the 3rd example be -14.2m/s since it's going down?
Yes, going down should be negative. Even the Ninja makes silly mistakes
Speed before hitting group is just 11.719
m/s
Total flight time should be the time you throw the ball up plus the time it lands on the ground right?
Yes
I have question sir how did you get 7
Is throwing a free fall?
How you get 1.2 seconds?
Top notch
I hope I get an answer real quick 🙏 I really need this..
On 12:11 why does the 9.8 became a denominator? I really didn't understood how the 0=6-9.8t became t=6/9.8. How did it happen??
In my understanding, to isolate t, it should be -6+9.8=t. But it became 6/9.8 here. Please somebody explain🥺
0=6-9.8t
9.8t=6
(9.8t)/9.8=(6)/9.8
(1)t=6/9.8
Basically just change the place, hope you get it👍🏼
@@GoodBoiy Good boy Good boy 😂
Thank you so much holy shizz
I guess dropping an object from a hot air balloon wouldn't have a initial velocity as zero right? Dropping from a stationary object, initial velocity will be zero
The clarification I seek,is dropping an object from a moving object would not have a zero as it's initial velocity
That’s right
Have you ever heard g=-9.81 instead of a=-g? this happen in now malaysia spm physics, and the teachers are still think it is right
what do you use to find 13.16 m/s
number 2 situation.
did we ever figure this out bc i am lost aswell 16:13
Hey you didn't take air resistance into account..
Good day sir! I have a question, how did you get the 2.7 in the problem A?
2.7 is not decimal but he said 2times 7 or 2*7
I am so confuse for the sign of g ,😢 is that if the ball is throw going down ,so the g is negative?and if the ball is going up ,so the g is positive?,can someone explain it to me ,thank you
There is always a negative force around if we throw something up, that force is called gravity.
4:55 why is t=1.96 secs??
Hello, I have a physics problem that I am willing to bet you are unable to solve. No calculations needed, just an understanding of the basic concepts of physics. What the puzzle is asking can be understood in just a moment.
If you reply, let me know if you want to attemp this puzzle. If you have a question about anything at all, something that interests you perhaps, ask. I am busy though. I am trying to save the world and there seems to be a lot of work that needs to be done. Puzzle is first concern here, but if I have time, would not mind chatting.
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Problem 2
Isn't that equation wrong? For vf^2 it's supposed to be plus 2g delta not minus