Mass, Weight and the local acceleration due to gravity

In summary, the conversation discusses determining the local acceleration of gravity and the mass and weight of a person weighing 150lb with a force of 144.4 lbf. Using the equation F=ma, the local acceleration of gravity is calculated to be 0.963 ft/s2, which seems low. The person's mass is given as 150lb and the weight is calculated to be 4826 lbf. It is noted that this weight is already given and the question may be asking for a different value.
  • #1
Northbysouth
249
2

Homework Statement


A person whose mass is 150lb weighs 144.4 lbf. Determine a) the local acceleration of gravity, in ft/s2, and b) the persons mass, in lb and weight, in lbf, if g = 32.174 ft/s2


Homework Equations


F=ma


The Attempt at a Solution


A) Using F=ma I got

144.4 lbf = (150lb)a
a = 0.963 ft/s2

My answer seems kinda low. Am I missing something?

b) F=ma

mass = 150lb

F = (150lb)(32.174 ft/sec2)
F = weight = 4826 lbf

I also feel like I'm missing something here as well, especially as it asks for the mass, which is already given. Am I misreading the question or something?

Any help would be appreciated. Thanks
 
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  • #2
Hint: if you'd been told the person weighed just a little more, 150 lbf, what would the answer have been?
 

What is the difference between mass and weight?

Mass is a measure of the amount of matter an object contains, while weight is a measure of the force of gravity acting on an object. Mass is constant and does not change depending on location, while weight can vary depending on the strength of gravity in a given location.

How is weight affected by the local acceleration due to gravity?

The local acceleration due to gravity, often denoted as "g", determines the strength of the gravitational force on an object. The weight of an object is directly proportional to g, meaning that as g increases, so does the weight of the object.

Can an object have a different mass and weight on different planets?

Yes, an object can have a different mass and weight on different planets. This is because the strength of gravity on each planet is different, which affects the weight of the object. However, the mass of the object remains constant regardless of location.

How is the local acceleration due to gravity measured?

The local acceleration due to gravity can be measured using a device called a gravimeter. This instrument measures the gravitational force on an object and can calculate the local acceleration due to gravity using this measurement.

Can the local acceleration due to gravity change over time?

Yes, the local acceleration due to gravity can change over time due to various factors such as changes in the Earth's rotation, tides, and shifts in the Earth's crust. However, these changes are usually very small and can be accounted for in scientific measurements.

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