A diver dives from the top of a 100m cliff. he begins his dive by jumping up with a velocity of 5m/s how long does it takes for him to hit the water below?

Free-fall Motion:

When an object is projected upwards from the top of a building, we can easily see that it progresses upwards until it comes to a halt. After that, the object commences its motion downward, and we should always recall that both the upward motion and the downward motion (falling motion) of the object are appreciated as free-fall motion. The kinematic equations could be used to investigate the free-fall motion of the object.

Answer and Explanation:

Given Data:

• {eq}u= \rm +5 \ m/s {/eq} is the initial velocity of the diver in the upward direction.
• {eq}h= \rm 100 \ m {/eq} is the height of...

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Learn more about this topic:

Solving Physics Problems Using Multiple Kinematic Equations

from

Chapter 5 / Lesson 5

There are five standard kinematics equations used to address kinematic problems in physics. Explore how to apply these equations to physics problems, how to combine multiple equations, and how to determine which equations to use.

A cliff diver stands at the top of a cliff and falls forward off the cliff. If the cliff is 25 m tall, how fast (in m/s) is the diver going as she enters the water below, and how long (in s) did the diver fall before reaching the water?

When the diver falls, he is in free-fall and the gravitational acceleration is acting on him.Freefall motion is nothing but accelerating motion with the acceleration {eq}g=9.8\ \rm m/s^2 {/eq}. Using kinematics we will solve the problem.

Answer and Explanation:1

This problem is based on the free-fall motion.

The velocity of a free-falling object after falling a height {eq}h {/eq} is given by...

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Learn more about this topic:

Free Fall in Physics | Definition, Equation & Examples

from

Chapter 4 / Lesson 10

Learn about free fall and its assumptions. Understand the free fall kinematics equation of an object with the help of examples.

In summary, the final velocity of a free falling object can be positive or negative depending on how you define the sign convention. In the given example, if down is defined as negative, then the final velocity of the cliff diver would be -44.6m/s. However, if up is defined as negative, then the final velocity would be 44.6m/s. The sign convention is arbitrary and the answer may change based on how it is defined.

• Feb 9, 2010

• 1

just a quick question! will the final velocity of a free falling object always be negative even if the answer is positive?

• Feb 9, 2010

• 2

  just a quick question! will the final velocity of a free falling object always be negative even if the answer is positive?

Hi, welcome to PF!

Sign conventions are arbitrary. It's up to you whether you define "up" to be the positive direction, or "down" to be the positive direction.

That having been said, if you have defined "down" to be negative, and you know that an object is supposed to be moving downward, yet you get a positive answer for its velocity, then your answer is incorrect given the sign convention you chose.

• Feb 9, 2010

• 3

  just a quick question! will the final velocity of a free falling object always be negative even if the answer is positive?

Not sure what you mean by 'final' velocity, but something in freefall can be moving up or down depending upon the exact problem. (Or not moving at all, for an instant.)

• Feb 9, 2010

• 4

thanks so much! that's what i thought, but then there's this question i was trying out (don't worry, it's not homework. found it online so i could practice):

A cliff diver from the top of a 100 [m] cliff. He begins his dive by jumping up with a velocity of 5 [m/s]. What is his velocity right before he hits the water?

if down is defined as negative and the equation used is vf^2=vi^2+2ad then the answer should be 44.6m/s but the answer on the site was -44.6m/s.

• Feb 9, 2010

• 5

  if down is defined as negative and the equation used is vf^2=vi^2+2ad then the answer should be 44.6m/s but the answer on the site was -44.6m/s.

He's moving down so his velocity should be negative. The site's answer is correct.

• Feb 9, 2010

• 6

i MUST be doing something wrong.@_@ or I'm inputting something wrong in my calculator. so the square root of 5^2 + 2(-9.8)(-100) is positive?

• Feb 9, 2010

• 7

  i MUST be doing something wrong.@_@ or I'm inputting something wrong in my calculator. so the square root of 5^2 + 2(-9.8)(-100) is positive?

The calculator only gives you the positive square root of a number. You have to supply the negative sign based on your understanding of how he's moving. (Don't forget that a negative number squared is positive.)

• Feb 9, 2010

• 8

  You have to supply the negative sign based on your understanding of how he's moving. (Don't forget that a negative number squared is positive.)

that's totally the answer to my first question.=D thanks!

1. How do you calculate the final velocity of a free falling object?

The final velocity of a free falling object can be calculated using the formula: Vf = Vi + at, where Vf is the final velocity, Vi is the initial velocity (usually 0 in free fall), a is the acceleration due to gravity (9.8 m/s^2), and t is the time in seconds.

2. What is the acceleration due to gravity?

The acceleration due to gravity is a constant value of 9.8 m/s^2, which means that for every second an object falls, its velocity will increase by 9.8 meters per second.

3. Does the mass of the object affect the final velocity?

No, in a vacuum, the mass of an object does not affect its final velocity in free fall. All objects will fall with the same acceleration due to gravity regardless of their mass.

4. How does air resistance affect the final velocity of a falling object?

Air resistance, or drag, can slow down the acceleration of a falling object. As the object falls, it will eventually reach a terminal velocity where the force of air resistance equals the force of gravity, causing the object to no longer accelerate.

5. Is the final velocity of a free falling object always downward?

Yes, in most cases, the final velocity of a free falling object will always be downward, towards the center of the earth. This is due to the force of gravity pulling the object towards the ground.

How high do cliff divers dive from?

Cliff divers dive from heights that range from 18 to 27 meters in the air (approximately 57-86 feet high). This height difference is significant, and affects the dive in several ways: Speed: A diver from 10 meters will hit the water at a speed of approximately 30 miles per hour (mph).

How fast would you reach the water if you jump off a cliff?

The speed or velocity of jumping into the water from some of the heights that people typically jump from is considerably faster than the rate that the average person can run. It's estimated that a jump into the water from only 20 feet will result in hitting the water at 25 miles-per-hour.

Why don t cliff divers go head first?

The height and speed of cliff diving and the pure forces inflicted on the divers' bodies on entering the water means that they have no choice but to sign off the dive by entering the water feet-first, unlike in Olympic diving where they typically enter the water head-first.