How Do Newton's Laws Apply to Multiple Objects in Motion?

In summary, the conversation discusses the calculation of acceleration and contact forces between three crates with varying masses, an applied force, and a coefficient of friction. The formulas used include weight, normal force, frictional force, and net force. In addition, another problem is mentioned involving tension forces between connected crates with given masses, acceleration, and friction. The formula used in this problem is T = 2MA, but the direction of the force and arrangement of the masses is not clear.
  • #1
tigerwoods99
99
0

Homework Statement



Three crates are arranged. The masses of the crates are m1= 29.8kg, m2= 15.3kg, and m3=27.3kg. The applied force of 910 N is directed horizontally, and the coefficient of friction is u= .277. what is the acceleration of the three masses and the magnitude of the contact force between m1 and m2, and m2 and m3

Homework Equations





The Attempt at a Solution



Weight of m1= 292.04
normal force on m2 = 150
FF on m1 = 80.9
FF on m2 = 150
Ff on m3= 74.1
 
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  • #2
FF on m2 is wrong.
Net force = applied force - FF.
Acceleration = Net force/ mass
 
  • #3
Thanks! Thats what I tried mathematically but resulted with the wrong answer becuase I didn't multiply M2 by the resistance..
 
  • #4
And what about the contact forces?
 
  • #5
If T1 is the contact force between M1 and M2, them
T1 - FF(M1) = M1a.
Similarly you can find T2.
 
  • #6
rl.bhat said:
If T1 is the contact force between M1 and M2, them
T1 - FF(M1) = M1a.
Similarly you can find T2.

ok so FF of M1= 80.89
FF of M2= 41.5
and the acceleration would equal 9.85m/s/s

so T1- 122.4(29.8)= (29.8)(9.85) ? That seems way to ghih.
 
  • #7
From where did you get 122.4?
It should be
T1 - 80.89 = 29.8*9.85.
In the formula FF(M1) is the frictional force on mass 1.
 
  • #8
so T1 would equal 374.42 The question asks what is the contact force between m1 and m2. 374.42 does not answer any of these questions. I have a feeling it has something to do with the friction source but I am not sure.. Thanks!
 
  • #9
Additionally, I have another question regarding a different problem.
Three crates are connected with ropes and arranged. The masses of the crates are m1= 20kg m2= 16.2kg and m3= 26.6kg. The crates accelerate to the right at 4.05m/s/sand the fiction is 0.279.

what is the magnitude of the tension force on the rope between m1 and m2 = 293.22
T= 2MA
T= 2(16.2)(4.05
T= 293.22N

What is the magnitude of the tension force in rope 2 between m2 and m3 ( m2====m2=====m1)
?
 
  • #10
In the first problem it is not clear to which mass the force is applied. Direction of the force decides the contact force.
In the second case how did you get T = 2MA?
Show the arrangement of the masses and the direction of the force clearly.
 

FAQ: How Do Newton's Laws Apply to Multiple Objects in Motion?

What are Newton's laws of motion?

Newton's laws of motion are a set of three fundamental principles that describe how objects move and interact with each other. They were developed by Sir Isaac Newton in the 17th century and are still used in modern physics to explain the behavior of objects in motion.

What is Newton's first law of motion?

Newton's first law of motion, also known as the law of inertia, states that an object at rest will remain at rest, and an object in motion will remain in motion at a constant velocity, unless acted upon by an external force.

What is Newton's second law of motion?

Newton's second law of motion states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. This can be expressed as the equation F=ma, where F is the net force, m is the mass of the object, and a is the acceleration.

How do Newton's laws apply to multiple objects?

When there are multiple objects involved, Newton's laws still apply individually to each object. However, the objects may also exert forces on each other, causing them to accelerate or change direction. The net force on an object is the vector sum of all the individual forces acting on it.

What is Newton's third law of motion?

Newton's third law of motion states that for every action, there is an equal and opposite reaction. This means that when one object exerts a force on another object, the second object will exert an equal and opposite force back on the first object. This can be seen in everyday situations, such as when a person pushes against a wall, the wall pushes back with an equal force.

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