Why Was FNetx Changed to ma in the Physics Problem?

  • Thread starter aprilrenee
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In summary, a 7980 N horizontal force was applied to a large telephone in the Netherlands in 1988, resulting in an acceleration of 1.33 m/s^2. To calculate the mass of the telephone, the formula FNetx = ma was used, where FNetx represents the net force in the x direction and ma represents the force required to accelerate an object. This formula was derived from Newton's second law of motion, which states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. The final answer for the mass of the telephone was 2580 kg. The student also questioned the use of FNetx = ma and was given a hint
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aprilrenee
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Homework Statement


In 1988, a very large telephone was constructed in the NEtherlands. In order to move the phone, a 7980 N horizontal force was applied that result in an acceleration of 1.33 m/s^2 along level ground.


Homework Equations


I received this question on a practice test for my exam tomorrow. I also have the work (shown below.)

- I do not understand how/why FNetx was changed to ma.
Why was this done?

The Attempt at a Solution



FNety = Fw- W (0 because not moving vertically.)
FNetx = Fa-Fk
ma = Fa - (mu)mg
ma+ (mu)k mg = Fa
m (a+(mu)k g) = Fa
m = Fa / a+ (mu)k g
m = 7890 / [(1.33m/s^2) + (.180)(9.80m/s^2)]
m = 2579.18552 kg
m = 2580 kg

... So on and so forth.
 
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  • #2
aprilrenee said:
- I do not understand how/why FNetx was changed to ma.
Why was this done?
Here's a hint. What is Isaac Newton's second law of motion?
 

1. What is friction and how does it affect objects?

Friction is a force that occurs when two surfaces come into contact and move against each other. It acts in the opposite direction of an object's motion and can either slow down or stop the object's movement. It is caused by the roughness of the surfaces and the strength of the force depends on the types of surfaces and the amount of force applied.

2. How does the coefficient of friction affect the force of friction?

The coefficient of friction is a measure of how easily one surface slides against another. It is a unitless value that ranges from 0 (no friction) to 1 (very high friction). The higher the coefficient of friction, the stronger the force of friction will be. This means that the rougher the surfaces or the heavier the object, the more force is needed to move it.

3. What are some real-life examples of friction?

Friction is present in many everyday activities, such as walking (between your shoes and the ground), driving (between tires and the road), and writing (between the pen and paper). Other examples include rubbing your hands together to create heat, using sandpaper to smooth a surface, and the brakes of a car stopping a moving vehicle.

4. How is friction different from other types of forces?

Unlike other forces, such as gravity or electromagnetism, friction is a non-conservative force. This means that it converts mechanical energy (motion) into thermal energy (heat) and dissipates it. Friction also acts in the opposite direction of an object's motion, while other forces can act in any direction.

5. How can friction be reduced or increased?

Friction can be reduced by using lubricants, such as oil or grease, between two surfaces. This creates a slippery layer that reduces the roughness and allows for smoother movement. On the other hand, friction can be increased by increasing the weight of an object, making the surfaces rougher, or increasing the force pushing them together.

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