Problem 4 Why is a \(10-\mathrm{m}\) fall ... [FREE SOLUTION] (2024)

Table of Contents

Short Answer Step by step solution Understand the basic concept of deceleration Understand the difference in deceleration between water and concrete Apply the concept to the exercise References

Chapter 9: Problem 4

Why is a \(10-\mathrm{m}\) fall onto concrete far more dangerous than a 10 -mfall onto water?

Short Answer

Expert verified

A 10-m fall onto concrete is far more dangerous than onto water because concrete, being a hard and unyielding surface, causes the object to decelerate very quickly. This results in a higher impact force, causing more damage. On the other hand, falling into water provides a longer deceleration time, thereby lessening the impact force and potential injuries.

Step by step solution

Understand the basic concept of deceleration

When an object falls, it gains speed due to the gravitational pull. When the object hits the ground, it must decelerate to zero speed, the force experienced by the object is greater if it decelerates over a shorter period of time. This is because force is equal to the change in momentum (which depends on speed) over time (Force = Change in momentum/time). Higher the deceleration, higher the force.

Understand the difference in deceleration between water and concrete

When an object falls into water, the water provides resistance causing the object to slow down gradually. Since the object decelerates over a longer period of time when it lands on water, the force it experiences is less. On the other hand, when object strikes concrete, it comes to a stop almost immediately, implying a very high deceleration. Consequently, the force experienced by the object is much larger.

Apply the concept to the exercise

In the case of a 10-m fall on different surfaces, the initial speed of the fall and the distance fallen would be the same but the stopping time would drastically change. The stopping time on concrete would be almost instant while on water it would be longer. Hence, the force experienced in the concrete fall would be much greater, leading to more damage.