Log out Go to App
Go to App

Learning Materials

Features

Discover

Chapter 5: Problem 5

In the army. You are told by a friend in the army that the force you feel when you fire a gun is the same as the force felt by a sandbag hit by the bullet because the two forces are action-reactions pairs. Is this true?

Short Answer

Expert verified
Yes, the forces are the same magnitude due to Newton's Third Law.

Step by step solution

01

- Understand Newton's Third Law

Newton's Third Law states that for every action, there is an equal and opposite reaction. This means that the force exerted by the gun on the bullet is equal in magnitude and opposite in direction to the force exerted by the bullet on the gun.
02

- Identify Action-Reaction Pairs

The action-reaction pairs in this scenario are: (1) the force the gun exerts on the bullet and (2) the force the bullet exerts on the gun. Another pair is (1) the force the bullet exerts on the sandbag and (2) the force the sandbag exerts on the bullet.
03

- Compare the Forces on Gun and Sandbag

Since the forces are action-reaction pairs, the force exerted by the gun on the bullet is equal and opposite to the force exerted by the bullet on the gun. Similarly, the force exerted by the bullet on the sandbag is equal and opposite to the force exerted by the sandbag on the bullet.
04

- Conclude the Observations

Based on Newton's Third Law, it is true that the force you feel when you fire the gun is the same magnitude as the force felt by the sandbag when hit by the bullet, because they are both action-reaction pairs involving the bullet.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Start your free trial

Over 30 million students worldwide already upgrade their learning with Vaia!

Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Action-Reaction Pairs
Action-reaction pairs are a fundamental concept in physics, especially when discussing Newton's Third Law. When two objects interact, they exert forces on each other that are equal in magnitude but opposite in direction.
Examples of action-reaction pairs include:
  • The force a book exerts on a table and the force the table exerts on the book.
  • The force a swimmer exerts on water and the force the water exerts on the swimmer.
In the context of the army exercise, the gun and the bullet form an action-reaction pair, as do the bullet and the sandbag. When the gun fires the bullet, the bullet pushes back on the gun with an equal and opposite force.
Forces in Firearms
When firing a gun, there are two main action-reaction pairs at play.
The first pair involves the gun and the bullet:
  • The gun exerts a force on the bullet, propelling it forward.
  • The bullet exerts an equal and opposite force on the gun, causing recoil.
The second pair involves the bullet and the target (sandbag in this case):
  • The bullet hits the sandbag, exerting a force on it.
  • The sandbag exerts an equal and opposite force back on the bullet.
It is crucial to note that while the forces are equal in magnitude, their effects can be different due to the mass and other properties of the objects involved. For example, the bullet's high velocity can cause significant damage to the sandbag, even though the force exerted on it by the sandbag is of equal magnitude.
Equal and Opposite Forces
Newton's Third Law is often summarized as: 'For every action, there is an equal and opposite reaction.' This law underpins much of what we observe in mechanics.
When analyzing the forces:
  • We see that the gun and bullet exert forces on each other that are equal in magnitude but opposite in direction.
  • The same is true for the forces between the bullet and the sandbag.
To better understand, consider the following example: If you push against a wall, the wall pushes back against you with an equal force. Similarly, in a gun-firing scenario, the bullet and the gun interact with forces that are equal and opposite, as do the bullet and the sandbag.
This concept helps us understand why the recoil of a gun is felt in the opposite direction to the bullet's travel.

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

Air resistance. You throw a ball straight up and measure the velocity as it passes you on its way down. Will the velocity be larger, the same, or smaller if you did the same experiment in vacuum?

Forces on a drop of water. A drop of water is hanging from a faucet. (a) Identify the forces acting on the drop and draw a free-body diagram of the drop. The drop finally falls down towards the sink. (b) Identify the forces acting on the drop and draw a free-body diagram of the drop.

Experiments in Pisa. On a visit to Pisa, you decide to redo Galileo's original experiment based on your knowledge of physics. You bring to steel spheres of the same size to the top of the tower. One sphere is hollow and the other is solid. (a) Draw a free-body diagram for one of the spheres. (b) How would you describe air resistance for each of the spheres? (c) Find an expression for the acceleration of the sphere as a function of its mass. (d) Which of the two spheres have the largest acceleration?

Zero velocity. If you throw a ball vertically it has zero velocity at its maximum point. Does it also have zero acceleration at this point?

Jumping into snow. Albert jumps from the roof of his house into a deep pile of snow. He starts \(5 \mathrm{~m}\) above the snow, and stops \(1 \mathrm{~m}\) into the snow. What force was exerted on Albert? Albert's mass is \(m=70 \mathrm{~kg}\). You can ignore air resistance, and you can assume that the force on Albert from the snow is constant.
See all solutions

Recommended explanations on Physics Textbooks

Scientific Method Physics

Read Explanation

Magnetism

Read Explanation

Circular Motion and Gravitation

Read Explanation

Famous Physicists

Read Explanation

Electrostatics

Read Explanation

Turning Points in Physics

Read Explanation
View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.

Sign-up for free