# Solving Friction Problem: Accelerating Wounded Soldier Out of Line of Fire

• bob24
In summary, a wounded soldier weighing 180 lbs is pulled away from danger by his comrade with a force of 70 lbs at a 65 degree angle. The coefficient of friction between the soldier and the ground is 0.55. After converting to SI units, the frictional force is calculated to be 64.108 N. Using the equation F-f=ma, the horizontal component of the applied force is found to be -6.176 ft/s^2, indicating that the soldier will not be able to be accelerated away from danger. It is advised that the comrade seek shelter instead.
bob24

## Homework Statement

A wounded soldier caught in Line of fire is pulled away by his comrade with a force of 70lbs at 65 degrees. The wounded solider(with his gear) weighs 180 lbs and the coefficient of friction between him and ground is .55
How quickly will he be accelerated out of harms way?

## Homework Equations

u=coefficent of friction
f=uF, w=mg, F-f=ma

## The Attempt at a Solution

f=uFn
f=(.55)(180-64.44lbs)
f=64.108lbs

w=mg
180=m(32.2)
5.59kg=mass

I don't know what to do(correctly) after this. Have I done anything wrong in the steps shown above?

There are two components to the force applied.

The vertical component lessens the frictional load.
The horizontal component is what you will have offset by the frictional drag.

Personally I would convert straight away to SI units.

1 lb force = 4.448 N

Our teacher wants us to keep the values like I have put there though. What should I do after finding the friction?
Do I use F-f=ma? If I do this, the answer I get is -6.176 ft/s(squared). So that means that he won't be accelerated away right?

If the horizontal component of the applied force is less than the maximum needed to overcome friction ... then whoever is doing the pulling should seek shelter.

Ok thank you!

## 1. What is friction and how does it affect the motion of a wounded soldier?

Friction is a force that opposes motion between two surfaces that are in contact. In the case of a wounded soldier, friction can slow down or impede their movement, making it difficult to quickly get out of the line of fire.

## 2. How can the amount of friction be calculated in this scenario?

The amount of friction can be calculated using the equation F=μN, where F is the force of friction, μ is the coefficient of friction, and N is the normal force. The coefficient of friction depends on the materials of the surfaces in contact and can be determined through experiments or research.

## 3. What factors should be considered when solving a friction problem for a wounded soldier?

When solving a friction problem for a wounded soldier, factors such as the weight of the soldier, the type of terrain they are on, and the amount of force being applied to move them should be taken into account. Additionally, the presence of any obstacles or other external forces should also be considered.

## 4. How can friction be reduced in order to accelerate a wounded soldier out of the line of fire?

Friction can be reduced by using lubricants, such as oils or greases, between the surfaces in contact. Additionally, reducing the weight of the soldier or using smoother surfaces can also help decrease the amount of friction.

## 5. What are some potential challenges when solving a friction problem for a wounded soldier?

Some potential challenges when solving a friction problem for a wounded soldier include accurately determining the coefficient of friction for the specific surfaces in contact, accounting for unpredictable or changing terrain, and ensuring the safety and comfort of the wounded soldier during the acceleration process.

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