# Calculate Velocity of 100 lb Block Dropped onto Stiff Spring

• the_d
In summary, the conversation discusses how to find the velocity of a block of mass 100 lb being dropped onto a spring with a stiffness of 100 lbs/ft after the spring has deformed 4 in. The conversation mentions using the equations for total energy and conservation of energy to solve the problem.
the_d
How do i find the velocity of a block of mass 100 lb being dropped a distance 5 ft onto a spring whose stifness is 100 lbs/ft after the spring has deformed 4 in?

im sure it has somthing to do with work of a spring force but i don't know exactly how. any ideas?

Can you write equations for the total energy of the mass and spring (kinetic and potential) before being dropped and at the moment the spring is deformed 4"? If you can, then you are well on your way to solving the problem.

ok ill see what i can do, thanx

do i use T1 + U = T2?

How does the work done by gravity relate to the work done by the spring force?

its in the opposite direction

What do they sum to?

Dorothy Weglend said:
What do they sum to?
zero.....

Well, there you go then. Problem solved.

No reason to think that the work done by the spring force will equal the work done by gravity. Note that it doesn't say that 4 in is the maximum compression of the spring... the block keeps going!

Instead, consider conservation of energy (assume no energy is lost when the falling block hits the "massless" spring). What's the initial energy of the block just as its being dropped? What's the final energy of the block + spring system when the spring has been depressed 4 in?

good explanation, i think i got it now thanks 4 help

## 1. How do you calculate the velocity of a 100 lb block dropped onto a stiff spring?

The velocity of a 100 lb block dropped onto a stiff spring can be calculated using the equation v = √(2gh), where v is the velocity, g is the acceleration due to gravity (9.8 m/s^2), and h is the height from which the block is dropped.

## 2. What is the formula for calculating velocity in this scenario?

The formula for calculating velocity of a 100 lb block dropped onto a stiff spring is v = √(2gh), where v is the velocity, g is the acceleration due to gravity (9.8 m/s^2), and h is the height from which the block is dropped.

## 3. What is the unit of measurement for velocity in this calculation?

The unit of measurement for velocity in this calculation is meters per second (m/s).

## 4. Can this calculation be used for different weights or springs?

Yes, this calculation can be used for different weights and springs as long as the values for g and h are adjusted accordingly. It is important to note that this equation assumes a constant acceleration due to gravity and a linear relationship between the weight and the spring force.

## 5. What factors can affect the accuracy of this calculation?

The accuracy of this calculation can be affected by factors such as air resistance, friction, and the stiffness of the spring. These factors can cause the velocity to be slightly different from the calculated value.

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