# Gravitational force, springs, and mass

• dragon162
In summary, the student is trying to solve for the spring force and doesn't know how to get k. The gravitational force is 0.1 kg * 9.8m/s^2 = 0.98 N.
dragon162

## Homework Statement

Suppose that I hang a 100 gram mass from a spring. When I do this, I find that the srping stretches 10 centimeters.

1)What is the gravitational force on the mass that I hang from the spring? give your answer in Newtons

2)what is the force that the spring is exerting on the mass?

F=-ky
F=mg

## The Attempt at a Solution

ok so I figured most of the problem out, I know that its a simple problem but I am just stuck on the first part and don't really know how to begin the second question. What I did was use the two equations i gave to solve for g=-ky/m but my problem is i don't know what k is or how to get it. As for the second part, i just have no idea how to start it. Thanks for any help in advance.

Last edited:
The gravitational force is just mg.

For the second part, if the spring-mass system is at rest when the spring is stretched 10 cm, what does that mean the spring force has to be at 10 cm?

jhae2.718 said:
The gravitational force is just mg.

For the second part, if the spring-mass system is at rest when the spring is stretched 10 cm, what does that mean the spring force has to be at 10 cm?
So, all I have to do is use the 100 grams and the acceleration due to gravity, 9.8. So (100g)(9.8)=980 and then just convert that to N?

For the second part, doesn't that mean that the spring force has to be at equilibrium so its at zero?

bump anymore help please have things to do today so I need to get this done early. Thanks for anyhelp in advance

You're correct on the first part. The gravitational force is 0.1 kg * 9.8m/s^2 = 0.98 N.

For the second part, we treat the system as if it were in equilibrium, so the sum of the forces must be zero. The spring force is nonzero.

jhae2.718 said:
You're correct on the first part. The gravitational force is 0.1 kg * 9.8m/s^2 = 0.98 N.

For the second part, we treat the system as if it were in equilibrium, so the sum of the forces must be zero. The spring force is nonzero.

Well since the sum will be zero then the spring force must cancel out the effect of gravity. So would it be 9.8 to counter the -9.8m/s^2.

dragon162 said:
Well since the sum will be zero then the spring force must cancel out the effect of gravity. So would it be 9.8 to counter the -9.8m/s^2.

You're talking about acceleration instead of force when you refer to gravity. The force of gravity is W=mg, where g=9.8m/s^2. (Sign is based on coordinate system, but it always points "down".)

So, the magnitude of the spring force when the displacement is 10 cm is equal to mg in this case.

jhae2.718 said:
You're talking about acceleration instead of force when you refer to gravity. The force of gravity is W=mg, where g=9.8m/s^2. (Sign is based on coordinate system, but it always points "down".)

So, the magnitude of the spring force when the displacement is 10 cm is equal to mg in this case.

Ah ok I understand it now. Thanks for all your help kind sir and have a nice day.

## 1. What is the relationship between mass and gravitational force?

The gravitational force between two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.

## 2. How does the strength of a spring relate to the mass attached to it?

According to Hooke's Law, the force exerted by a spring is directly proportional to the displacement from its equilibrium position. Therefore, the stronger the spring, the greater the force it can exert on a given mass.

## 3. Can gravitational force and spring force cancel each other out?

Yes, if an object is suspended by a spring and is in equilibrium, the forces acting on it must be balanced. This means that the weight of the object due to gravitational force is equal in magnitude but opposite in direction to the force exerted by the spring.

## 4. How does the mass of an object affect its acceleration due to gravity?

According to Newton's second law of motion, acceleration is directly proportional to the net force acting on an object and inversely proportional to its mass. Therefore, the greater the mass of an object, the smaller its acceleration due to gravity will be.

## 5. Can the strength of a spring be changed by altering the mass attached to it?

Yes, the strength of a spring can be changed by adding or removing mass from it. This is because the force exerted by a spring is directly proportional to its displacement from equilibrium, which can be altered by changing the mass attached to it.

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