According to Eq. 7–4, the longer the impact time of an impulse, the smaller the force can be for the same momentum change, and hence the smaller the deformation of the object on which the force acts. On this basis, explain the value of air bags, which are intended to inflate during an automobile collision and reduce the possibility of fracture or death.

Short Answer

Expert verified

The airbags will reduce the amount of force exerted on the occupants inside the car by increasing the impact time.

Step by step solution

01

Understanding the impulse-momentum equation

Equation 7-4 can be written as:

\(F\Delta t = \Delta p\)

Here, Fis the net force,\(\Delta t\)is the time interval, and\(\Delta p\)is the change in momentum.

According to this equation, the change in momentum on a system equals force multiplied by time. If we increase the time of impact, the force reduces.

02

Explanation of the importance of airbags in automobile

The airbags in an automobile increase the time of impact from the moment of the accident to when a person collides with the interior of the automobile.This increase in time can reduce the magnitude of the impact force that a person has to wear. Hence, the amount of force acting over a long period of time is smaller. Therefore, it minimizes the possibility of fracture or death.

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Most popular questions from this chapter

The speed of a tennis ball on the return of a serve can be just as fast as the serve, even though the racket isn’t swung very fast. How can this be?

When a high jumper is in a position such that his arms and lower legs are hanging vertically, and his thighs, trunk, and head are horizontal just above the bar, estimate how far below the torso’s median line the CM will be. Will this CM be outside the body? Use Table 7–1.

A bullet of mass \(m{\bf{ = 0}}{\bf{.0010}}\;{\bf{kg}}\) embeds itself in a wooden block with mass \(M{\bf{ = 0}}{\bf{.999}}\;{\bf{kg}}\), which then compresses a spring \(\left( {k{\bf{ = 140}}\;{\bf{N/m}}} \right)\) by a distance \(x{\bf{ = 0}}{\bf{.050}}\;{\bf{m}}\) before coming to rest. The coefficient of kinetic friction between the block and table is \(\mu {\bf{ = 0}}{\bf{.50}}\).

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Three cubes, of side \({l_ \circ }\), \(2{l_ \circ }\), and \(3{l_ \circ }\), are placed next to one another (in contact) with their centers along a straight line as shown in Fig. 7–38. What is the position, along this line, of the CM of this system? Assume the cubes are made of the same uniform material.

FIGURE 7-38

Problem 52.

You drop a 14-g ball from a height of 1.5 m and it only bounces back to a height of 0.85 m. What was the total impulse on the ball when it hit the floor? (Ignore air resistance.)

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