Solving Hook's Law Problems with Gravity

In summary, the conversation discusses a physics problem involving Hook's law and an object connected to a spring and pulled by another object. The problem involves determining the applied force given the masses, spring constant, and compression distance of the spring. The conversation also mentions the need for a diagram and considering the horizontal forces on each crate.
  • #1
phillyj
30
0
hi everyone,
I'm stuck on a problem that uses Hook's law but it's not straight forward. What must i do when there is an object pulled by an another object and connected with a spring. do i have to combine the force due to gravity on each of the object? can someone tell me a reference site for this. thanks
 
Last edited:
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  • #2
phillyj said:
hi everyone,
I'm stuck on a problem that uses Hook's law but it's not straight forward. What must i do when there is an object pulled by an another object and connected with a spring. do i have to combine the force due to gravity on each of the object? can someone tell me a reference site for this. thanks

Could you provide a sketch? Start with a free body diagram. Gravity is acting on every body with non-neglible mass, right? That's a start point.
 
  • #3
heres the diagram. the bigger mass is connected to a small one by a spring with (k) given. A force pulls on the larger mass and the spring compresses a certain length from equilibrium.

http://img529.imageshack.us/img529/8886/physicio4.th.jpg

The problem is this: 2 crates, 640 kg and 490kg, are connected by a spring with k=8.1 kN/m and it's propelled along a level frictionless plane by a horizontal force of 15 N. The spring compresses 5.1 cm, what is the applied force?

I have no clue where to start.
 
Last edited by a moderator:
  • #4
anyone even understand how we would go about doing this?
 
  • #5
would a combination of F1m1=F2m2 and hook's law help?
 
  • #6
phillyj said:
heres the diagram. the bigger mass is connected to a small one by a spring with (k) given. A force pulls on the larger mass and the spring compresses a certain length from equilibrium.

http://img529.imageshack.us/img529/8886/physicio4.th.jpg

The problem is this: 2 crates, 640 kg and 490kg, are connected by a spring with k=8.1 kN/m and it's propelled along a level frictionless plane by a horizontal force of 15 N. The spring compresses 5.1 cm, what is the applied force?

I have no clue where to start.

You'll want to start by considering the horizontal forces acting on each crate. (Since there is no friction between the crates and the surface they slide on, we don't really need to know about the vertical forces, as we'll have no use for that information.)

I might note that if the spring is being compressed, the crates are presumably being pushed from behind; were they being towed from the front, the spring should be stretched. I don't think this changes the result, however.
 
Last edited by a moderator:

Related to Solving Hook's Law Problems with Gravity

What is Hook's Law?

Hook's Law is a principle in physics that describes the relationship between the force applied to an elastic material and the resulting displacement of that material.

How does gravity affect Hook's Law?

Gravity is a force that acts on all objects with mass, and it can affect the displacement of elastic materials according to Hook's Law. In some cases, the force of gravity may be negligible, but in others, it can significantly impact the displacement of an elastic material.

How do you solve problems involving Hook's Law and gravity?

To solve problems involving Hook's Law and gravity, you will need to use the equation F = kx + mg, where F is the total force, k is the spring constant, x is the displacement of the material, m is the mass of the object, and g is the acceleration due to gravity. You can rearrange this equation to solve for any of the variables.

What are some real-world examples of using Hook's Law and gravity?

Some real-world examples of using Hook's Law and gravity include calculating the displacement of a spring under the weight of an object, determining the stretchiness of a rubber band when hanging an object from it, and understanding the behavior of bungee cords.

What are some common mistakes when solving Hook's Law problems with gravity?

One common mistake is forgetting to account for the force of gravity when solving for the displacement of an elastic material. Another mistake is using the incorrect units for the variables in the equation (e.g. using kilograms instead of newtons for force). It is also important to pay attention to the direction of the forces and displacement, as this can affect the sign of the variables in the equation.

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