Water falling into bucket, Force question

In summary: The speed of the water as it hits the scale is v=d/t, and the time it takes for the water to fall is t=3.14 s. Therefore, the speed of the water as it falls is v=17.9 m/s.
  • #1
Leeoku
18
0

Homework Statement


13. Water falls at the rate of 271 g/s from a height of 56.2 m into a 776g bucket on a scale (without splashing). If the bucket is originally empty, what does the scale read after 3.14 s?
Answer: 2.50e+01 N



Homework Equations


Density, estimate 1kg/m^3
F = ma (a = gravity)
1kg = 1L


The Attempt at a Solution


In 3 seconds, .271*3 = .851 L dropped->.851 KG
Add weight of bucket, .851+.776 = 1.63 kg
F =ma
= 15.9 N
 
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  • #2
You found the weight of the water + bucket. Good! But an additional force is required to stop the momentum of the flowing water.
 
  • #3
i actually have no clue. what I am puzzled at is why they gave us distance. the first thing that comes to mind is work, but i don't think that helps..
 
  • #4
Leeoku said:
i actually have no clue. what I am puzzled at is why they gave us distance. the first thing that comes to mind is work, but i don't think that helps..
They gave you the distance so you can figure out the speed of the water as it hits the bucket. Hint: Use that speed to find the rate of change of the momentum of the water as it hits the bucket.
 
  • #5
ok using v=d/t, 56.2/3.14 = 17.9 m/s
Impulse = delta p = (sum F)delta T
Delta p = 15.9*3.14
= 50 N.s
Using 50 as momentum, p = mv
50 = 17.89 M
m = 2.8 kg

Weird part is answer is given in Newtons, so mass*g = 27.4 N. Still not right, close though..
 
  • #6
Leeoku said:
ok using v=d/t, 56.2/3.14 = 17.9 m/s
Two problems:
(1) The 3.14 s time given is not the time it takes for the water to fall from the given height.
(2) The speed of the water is not constant as it falls.

To find the speed of the water as it hits the scale, treat it as a falling body (falling from rest through a height of 56.2 m).
 

FAQ: Water falling into bucket, Force question

1. How does water falling into a bucket create a force?

As the water falls into the bucket, it gains momentum and increases in velocity. This increase in velocity creates a force, known as the force of impact, when the water hits the bottom of the bucket.

2. What factors affect the force of water falling into a bucket?

The force of water falling into a bucket is affected by the height from which the water falls, the mass of the water, and the shape and material of the bucket. These factors determine the velocity and momentum of the falling water, which ultimately determines the force of impact.

3. Can the force of water falling into a bucket be calculated?

Yes, the force of water falling into a bucket can be calculated using the formula F = m x a, where F is the force, m is the mass of the water, and a is the acceleration due to gravity. However, this calculation may be affected by other factors such as air resistance and the shape of the falling water.

4. Does the force of water falling into a bucket change if the bucket is filled to different levels?

Yes, the force of water falling into a bucket will be greater if the bucket is filled to a higher level. This is because the mass and velocity of the falling water will be greater, resulting in a stronger force of impact.

5. How does the force of water falling into a bucket compare to other forces?

The force of water falling into a bucket can vary greatly depending on the factors mentioned above. However, in general, it is a relatively weak force compared to other forces such as gravity, friction, and electromagnetism. It is also significantly weaker than the force of water hitting a surface at high pressure, such as a waterfall or a water jet.

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