Calculating Mass of Little Sister Using Newton's Second Law

In summary, when exerting a constant horizontal force of 110 N on a sled with a mass of 7 kg, the resulting acceleration of 2.5 m/s^2 can be used to calculate the mass of the person being pulled. By rearranging the formula, it is determined that the mass of the person is 37 kg.
  • #1
Propaganda777
10
0
You are pulling your little sister on her sled acroos an icy(frictionless) surface. When you exert a constant horizontal force of 110 N, the sled has an acceleration of 2.5 m/s^2. If the sled has a mass of 7 kg, what is the mass of your little sister?

Heres how I attempted it:
F=110N
A=2.5 m/s^2
M1= 7kg
M2= ?

F=(M1+M2) A
M2= 41.2 kg


The answer is 37 kg, but I can't figure out how to arrive at this mass. Can anyone help me?
 
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  • #2
Propaganda777 said:
F=(M1+M2) A
Since you know F and A, you can solve for M1 + M2. Then just subtract out M1.
 
  • #3
I did, but it comes out to a wrong answer:

F= (m1+m2)a

m2=(F-m1)/a

m2=41.2kg

The answer should be 37 kg, right?
 
  • #4
Propaganda777 said:
I did, but it comes out to a wrong answer:

F= (m1+m2)a

m2=(F-m1)/a
That last step doesn't follow. Do this:
F = (m1 + m2)a
F/a = m1 + m2

What's that equal?
 
  • #5
hey it works, thanks you:)
 

FAQ: Calculating Mass of Little Sister Using Newton's Second Law

What is Newton's Second Law?

Newton's Second Law, also known as the Law of Acceleration, states that the force acting on an object is equal to the mass of the object multiplied by its acceleration. In other words, the greater the force applied to an object, the greater its acceleration will be, and the larger the mass of the object, the smaller its acceleration will be.

How do I calculate force using Newton's Second Law?

To calculate force using Newton's Second Law, you need to know the mass of the object and its acceleration. The formula for force is F = ma, where F is force in Newtons, m is mass in kilograms, and a is acceleration in meters per second squared. Simply multiply the mass by the acceleration to find the force.

What are the units used in Newton's Second Law?

The units used in Newton's Second Law are Newtons (N) for force, kilograms (kg) for mass, and meters per second squared (m/s²) for acceleration.

Can Newton's Second Law be applied to any type of motion?

Yes, Newton's Second Law can be applied to any type of motion, whether it is linear, rotational, or orbital. As long as there is a force acting on an object, the law can be used to calculate its acceleration.

What is the relationship between force, mass, and acceleration in Newton's Second Law?

The relationship between force, mass, and acceleration in Newton's Second Law is direct and proportional. This means that the force applied to an object will directly affect its acceleration, and the mass of the object will have an inverse effect on its acceleration. The greater the force, the greater the acceleration, and the greater the mass, the smaller the acceleration will be.

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