When Valerie Volleyballer jumps to spike ball, she rises a total of 2 m in air after accelerating through 0.5 m (from the crouch to full extension). What is her acceleration during takeoff?
#Linear Motion
summer epoch
mild notch
Try using v² - u² = 2as during both journeys.
woven flume
Try using v² - u² = 2as during both journeys.
I write d instead of s, its the distance
4 - 0.25 = 2 x a x 2
3.25 = 2 x a x 2
a = 0.8125 m/s^2
mild notch
Hmmm? No no. You squared distances
summer epoch
It has been made impossible to find velocity. @everyone
Velocity depends on distance covered and time.
mild notch
Try using v² - u² = 2as during both journeys.
You can find tho.
mild notch
Why don't you try applying those suvat stuff
summer epoch
Why don't you try applying those suvat stuff
What suvat stuff?
knotty smelt
Why are you pinging everyone
summer epoch
@everyone, who has found the answer?
knotty smelt
There is like 20k people
summer epoch
There is like 20k people
I only need an immediate answer to my question that's all.
mild notch
What suvat stuff?
Equations of motion
woven flume
You can find tho.
Please help, I'm an amateur
mild notch
Accelerates during takeoff to get some velocity. Which would be initial velocity for journey without external acceleration other than g,
v² - u² = 2ad
0 - u² = 2(-g)(1.5)
u = sqrt(3g)
So, velocity gained through accelerated takeoff is sqrt(3g)
Again, v² - u² = 2ad
3g - 0 = 2a(0.5)
summer epoch
But deceleration occurs during upward motion.
summer epoch
Accelerates during takeoff to get some velocity. Which would be initial velocity...
So she accelerated at 40 m/s^2
mild notch
But deceleration occurs during upward motion.
Yeah that's why -g
mild notch
So she accelerated at 40 m/s^2
30?
mild notch
I don't see how it'd be 40
summer epoch
I don't see how it'd be 40
Yeah I know.
But It is it.
We are talking about deceleration.
mild notch
We are talking about deceleration.
You probably went wrong somewhere
summer epoch
Where?
mild notch
I wouldn't know unless you show your working on how you got 40
summer epoch
I wouldn't know unless you show your working on how you got 40
So that is where I went wrong?
summer epoch
I said I wouldn't know where it went wrong unless I see how you approached 40
So when substituted with 0.5 m as the distance, the acceleration is 40 m/s.
mild notch
Initial velocity is 2√10 m/s.
Why is initial velocity 2sqrt10
summer epoch
Why is initial velocity 2sqrt10
Because the deceleration is 10 m/s.
mild notch
Because the deceleration is 10 m/s.
Initial velocity as in at what point of journey.
summer epoch
Initial velocity as in at what point of journey.
There is no journey.
mild notch
As in, the person wasn't moving at all?
summer epoch
As in, the person wasn't moving at all?
In the question, Valerie moved upwards to spike the ball.
mild notch
Yeah, so corresponding to what height the velocity is 2sqrt10?
summer epoch
Yeah, so corresponding to what height the velocity is 2sqrt10?
Corresponding to 2 metres hight.
mild notch
2 metres is the maximum height. Where velocity is 0.
summer epoch
2 metres is the maximum height. Where velocity is 0.
I mean the constant velocity.
mild notch
Hmmm idk what you mean by constant velocity. Cuz velocity is changing constantly.
summer epoch
Constant velocity is when the rate of change of displacement with time remains equal.
summer epoch
Hmmm idk what you mean by constant velocity. Cuz velocity is changing constantly...
This question is a challenging one so it would need much analysis.
mild notch
Constant velocity is when the rate of change of displacement with time remains e...
Which is not a case in this question so that's irrelevant
summer epoch
But I found the answer to be 40 m/s^2
mild notch
This question is a challenging one so it would need much analysis.
Tbh it's not. I'd actually advise you to practice basic questions thoroughly so you have good conceptual understanding
mild notch
But I found the answer to be 40 m/s^2
You haven't given appropriate explanation to it
Guess you did v = sqrt(2×10×10) to get v = 2sqrt10. But that would be the case when it falls freely or thrown up through 2 meters. Question says that 0.5 m of that 2 is accelerated upwards.
tall owl
@summer epoch you probably set as acceleration a-g
Where a the acceleration due to the jump force
The total acceleration is 30 m/s²
The part coming from the jump force is 40m/s²
The question asks for the total so the answer is 30
summer epoch
@mild notch and @tall owl, OK.
summer epoch
Guess you did v = sqrt(2×10×10) to get v = 2sqrt10. But that would be the case w...
Nothing was thrown up.
mild notch
Nothing was thrown up.
Let's say she was thrown up. You lose nothing by saying that.
summer epoch
Let's say she was thrown up. You lose nothing by saying that.
Assumption is not accurate.
She rose to spike the ball with the hight of 2 m and accelerated 0.5 m.
mild notch
Bro are you concerned about the literature aspect
summer epoch
Yeah.
mild notch
I'd call it immature
summer epoch
Let us not assume things for we would be wrong.
mild notch
It was an analogy you don't lose any information required for the answer
mild notch
Accelerates during takeoff to get some velocity. Which would be initial velocity...
It's here
summer epoch
Accelerates during takeoff to get some velocity. Which would be initial velocity...
There is no understanding in what you have done there.
But at least you did your best. Thank you for that.
summer epoch
So what is the velocity is 30m/s?
tall owl
Velocity when h=0.5 m is sqrt(30) m/s
summer epoch
OK.
tall owl
I missed a m/s^2 square
summer epoch
You and Mark as read are giving me one answer.
tall owl
Yeah thats what the question asks
summer epoch
OK.
Are you aware you are you used 1.5 m to find the velocity?
Look @tall owl
√(2)(g)(h)=√(2)(1.5)(10)= √30 m/s.
I think you are supposed to use the total distance 2 m to find the velocity.
tall owl
Yeah h2-h1=1.5
summer epoch
But shouldn't you use the total distance?
tall owl
No the conservation of energy is done from point 1 to point 2, h1=0.5 m , h2=2 m
summer epoch
OK