Calculating Diver's Descent Distance

  • Thread starter xytos
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In summary, a 50.0 kg diver drops straight down into the water from a diving board with a resistant force of 1500N. The driver comes to rest 5.0m below the water's surface. To find the total distance between the board and the driver's stopping point underwater, the initial velocity and initial displacement are both assumed to be zero. Using the equation D=1/2mv^2/F, the diver's final velocity can be calculated. The next step is to analyze the motion in the water by setting a convenient point as the "zero" of displacement and using the equation Vi=Vf+2ad to find the numerical value of the unknown.
  • #1
xytos
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A 50.0 kg diver steps off a diving board and drops straight down into the water. The water provides an adverage net force resistance of 1500N to the driver's fall. If the driver comes to rest 5.0M below the water's surface, what is the total distance between the board and the driver's stopping point underwater?
The Given:
mass: 50.0kg
resistant force: 1500N​
Can someone tell me how to get velocity?? I've tried everything i could think of...
Vi=Vf+2ad;
D=1/2mv^2/F;

Anything else i can do??
 
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  • #2
I've deleted your other three threads that were identical to this one. One thread per question please.

xytos said:
The Given:
mass: 50.0kg
resistant force: 1500N​

You were given more than that. You were told that the diver's final velocity is zero, you were told that his initial velocity was also zero (that is implied by the word "drops"), and you were told that his final displacement is 5 m below the surface of the water.

Can someone tell me how to get velocity?? I've tried everything i could think of...
Vi=Vf+2ad;
D=1/2mv^2/F;
Anything else i can do??

I'm not going to just tell you how to do the problem (we don't do that here at Physics Forums) but what I will do is give you some helpful advice.

First of all: Don't just throw equations at the problem. Think about the problem.

OK, you've actually got two parts to this problem: The part where the diver is in the air, and the part where he's in the water. While he's in the air you can assume that the only force acting on him is gravity. While he's in the water you have two forces acting: gravity and the drag force from the water.

Now, you don't know how far it is from the board to the surface of the water, so you're going to have to represent that distance with a variable.

Try to answer these questions, in order. If you can do that then you can solve half of the problem.

1.) Set a convenient point to serve as the "zero" of displacement.
2.) Analyze the motion in the water first. What were you given?
3.) What were you asked for?
4.) What equation contains all of those quantities? Use that equation in the next step.
5.) What is the numerical value of the unknown?

Give that a shot. If you can complete step 5 then you will have solved half the problem, and then we can get to work on the other half.
 
  • #3


To calculate the diver's descent distance, we can use the equation d = (1/2)at^2, where d is the distance, a is the acceleration, and t is the time. In this case, we know the mass of the diver (50.0kg) and the net force resistance provided by the water (1500N). We can use Newton's second law, F=ma, to calculate the acceleration: a = F/m = 1500N/50.0kg = 30m/s^2.

Next, we need to calculate the time it takes for the diver to reach the stopping point underwater. We can use the equation vf = vi + at, where vf is the final velocity (which is 0 since the diver comes to rest) and vi is the initial velocity. We do not know the initial velocity, but we can calculate it using the equation vi = sqrt(2ad), where a is the acceleration and d is the distance traveled. In this case, d is 5.0m since that is the stopping point underwater. Plugging in the values, we get vi = sqrt(2*30m/s^2*5.0m) = 15m/s.

Now that we have the initial velocity, we can calculate the time it takes for the diver to reach the stopping point using the equation vf = vi + at. Plugging in the values, we get 0 = 15m/s + 30m/s^2*t. Solving for t, we get t = -0.5s. Since time cannot be negative, we can ignore this value and use the positive value, which is 0.5s.

Finally, we can use the equation d = (1/2)at^2 to calculate the total distance between the board and the diver's stopping point underwater. Plugging in the values, we get d = (1/2)*30m/s^2*(0.5s)^2 = 3.75m. Therefore, the total distance between the board and the diver's stopping point underwater is 3.75m.
 

1. How do you calculate a diver's descent distance?

The formula for calculating a diver's descent distance is: Descent Distance = (Descent Rate * Descent Time) + Initial Depth. The descent rate is typically 30 feet per minute, and the descent time is the time it takes for the diver to reach the desired depth.

2. What is the initial depth in the calculation for a diver's descent distance?

The initial depth is the depth where the diver begins their descent. It is typically measured in feet or meters and is added to the product of the descent rate and descent time in the formula for calculating descent distance.

3. How do you convert feet to meters for calculating a diver's descent distance?

To convert feet to meters, you can use the conversion factor of 1 foot = 0.3048 meters. So, if the initial depth is given in feet, you would multiply it by 0.3048 to get the equivalent depth in meters.

4. What is the standard descent rate for calculating a diver's descent distance?

The standard descent rate for calculating a diver's descent distance is 30 feet per minute. This is a safe and commonly used rate for recreational divers. However, professional divers may use a different descent rate depending on the circumstances.

5. How do you account for changes in depth during a diver's descent?

If there are any changes in depth during a diver's descent, you can adjust the descent time in the calculation to account for it. For example, if the diver reaches a depth of 20 feet and then descends an additional 10 feet, the descent time would be adjusted accordingly.

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