Weight in N with change in acceleration

In summary, a 2kg weight is suspended on a tension scale that measures in Newtons. The elevator is moving at a constant velocity of 10m/s, but then its velocity is uniformly reduced to zero in 4 seconds, causing it to come to rest. During these 4 seconds, the scale reads a tension force of 29.6N. However, according to the book, the correct tension force should be 14.6N. Upon further inspection, it is discovered that the initial equation used was incorrect. The correct equation should be Vf=Vi+at.
  • #1
lajekahr
2
0
2kg weight is suspended on a tension scale that measures in Newtons.
The elevator is moving at constant velocity up of 10m/s. Its velocity is then uniformly reduced to zero in 4 seconds. So that it comes to rest in 4 seconds. What does the scale read during those 4 seconds.

---------
Using frame of reference with positive down: (That way gravity's acceleration is positive.)
Using Kinematics:
Vf=Vi*t+1/2a*t^2
Therefore:
a=(-2Vi)/t=-5m/s^2
Applying F=ma:
Ftension+Fgravity=ma
-Ft+mg=ma
Ft=mg-ma=2*9.8-2*(-5)=29.6N

My books says: 14.6N

What'd I do wrong?
 
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  • #2
lajekahr said:
2kg weight is suspended on a tension scale that measures in Newtons.
The elevator is moving at constant velocity up of 10m/s. Its velocity is then uniformly reduced to zero in 4 seconds. So that it comes to rest in 4 seconds. What does the scale read during those 4 seconds.

---------
Using frame of reference with positive down: (That way gravity's acceleration is positive.)
Using Kinematics:
Vf=Vi*t+1/2a*t^2
Therefore:
a=(-2Vi)/t=-5m/s^2
Applying F=ma:
Ftension+Fgravity=ma
-Ft+mg=ma
Ft=mg-ma=2*9.8-2*(-5)=29.6N

My books says: 14.6N

What'd I do wrong?
Your first equation is wrong.
It should be Vf=Vi+at.
 
  • #3
Now i feel kinda dumb. I knew that I swear...that first equation is for displacement...doh!
 

1. What is the relationship between weight in Newtons and change in acceleration?

The relationship between weight in Newtons and change in acceleration is directly proportional. This means that as the acceleration increases, the weight in Newtons also increases. Similarly, as the acceleration decreases, the weight in Newtons decreases.

2. How is weight in Newtons affected by a change in acceleration?

Weight in Newtons is affected by a change in acceleration because weight is a force that is directly influenced by acceleration. This is due to Newton's Second Law of Motion, which states that force is equal to mass multiplied by acceleration. As acceleration changes, the force of weight also changes accordingly.

3. What units are used to measure weight in Newtons?

Weight in Newtons is typically measured in units of Newtons (N). This unit is derived from the SI unit of force, which is the Newton (N). Other units that are commonly used to measure weight include pounds (lb) and kilograms (kg).

4. How does weight in Newtons with change in acceleration differ from weight in kilograms with change in acceleration?

Weight in Newtons with change in acceleration differs from weight in kilograms with change in acceleration because they are measured using different units. Weight in kilograms is a measure of mass, while weight in Newtons is a measure of force. Therefore, the relationship between weight and acceleration is different for each unit, as mass and force have different properties.

5. Can weight in Newtons be negative with a change in acceleration?

Yes, weight in Newtons can be negative with a change in acceleration. This occurs when the acceleration is in the opposite direction of the weight. In this case, the weight is acting in the opposite direction of the acceleration, resulting in a negative value. However, it is important to note that weight is a vector quantity and is typically represented by a positive value for convenience.

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