How do you find answer in Newton?(read)

  • Thread starter DudewithSkull
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In summary, to find the reading on the scale in N when the elevator is accelerating downward at 6.7 m/s2, you need to use the equation mg - ma = reaction force. In this case, the reaction force would be equal to 480 N - (480 kg * 6.7 m/s2) = 480 N - 3216 N = -2736 N. Therefore, the scale would be reading a downward force of 2736 N.
  • #1
DudewithSkull
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Homework Statement


A person of weight 480 N stands on a scale in an elevator. What will the scale be reading in N when the elevator is accelerating downward at 6.7 m/s2 ?


Homework Equations


N= kg(m/s^2)


The Attempt at a Solution


Tried 480/9.81 = 48.929 times 6.7 equal 328 N
Is this the right equation? If not, please tell me what equation or how to solve problem like this. Thank you.
 
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  • #2
i'm afraid that's not right, if you think about it in net force;

The net force is given by ma, which you worked out to be 328N;

however this isn't what you're looking for, you're looking for the reaction from the floor of the lift on the person, you know that the net force is equal to the persons weight (downwards) minus the reaction force (upwards)

[tex] ma (net force) = mg (weight) - reactionforce (reading on scale) [/tex]
 
  • #3


I would approach this problem by using the fundamental principles of Newtonian physics. First, we need to understand that weight is the force exerted by an object due to gravity, and it is measured in Newtons (N). In this case, the person's weight is given as 480 N.

Next, we need to consider the elevator's acceleration, which is given as 6.7 m/s^2 downward. This means that the elevator is accelerating downwards at a rate of 6.7 meters per second squared. This acceleration is caused by the force of gravity on the elevator and the person inside it.

To find the scale reading, we need to use the equation F=ma, where F is the force, m is the mass, and a is the acceleration. In this case, the force (F) is the person's weight (480 N), the mass (m) is unknown, and the acceleration (a) is 6.7 m/s^2.

Rearranging the equation to solve for mass, we get m=F/a. Substituting the values, we get m=480 N / 6.7 m/s^2 = 71.64 kg.

Now, we can use the equation N=kg(m/s^2) to find the scale reading in Newtons. Substituting the values, we get N= 71.64 kg x 6.7 m/s^2 = 480.988 N. Therefore, the scale reading will be approximately 481 N when the elevator is accelerating downward at 6.7 m/s^2.

In conclusion, to find the answer in Newtons, we need to use the fundamental principles of Newtonian physics and the relevant equations to solve the problem. It is important to understand the concepts and units involved in order to arrive at the correct answer.
 

1. How did Newton come up with his laws of motion?

Isaac Newton developed his laws of motion through a combination of observation, experimentation, and mathematical calculations. He was inspired by the work of other scientists, such as Galileo and Kepler, and used their principles to develop his own laws.

2. What are the three laws of motion according to Newton?

Newton's three laws of motion are: 1) 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, 2) force equals mass times acceleration, and 3) for every action, there is an equal and opposite reaction.

3. How do Newton's laws of motion apply to everyday life?

Newton's laws of motion can be observed in everyday life in various ways. For example, the first law can be seen when a car comes to a stop when the brakes are applied, and the second law can be seen when a person pushes a shopping cart and it accelerates. The third law can be seen when a rocket launches by pushing exhaust gases downward, causing the rocket to move upwards.

4. What is the role of gravity in Newton's laws of motion?

Gravity is a force that is described by Newton's laws of motion. It is responsible for the acceleration of objects towards the Earth and is included in the second law as the force that acts on an object to cause it to accelerate. Gravity also plays a role in the third law, as it is responsible for the equal and opposite reaction force when an object is pushed or pulled.

5. How do we use Newton's laws of motion in scientific research?

Newton's laws of motion are fundamental principles in physics and are used to understand and predict the motion of objects in various scenarios. They are used in scientific research to study the movement of celestial bodies, the behavior of fluids, and the dynamics of machines and structures. They also play a crucial role in the development of technologies, such as rocket propulsion and vehicle design.

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