# Pile driver question kinetic energy and potential energy

• dansbr
In summary, the conversation discusses the calculation of the kinetic energy and change in potential energy of a pile driver and steel pile after impact. The velocity is assumed to be 0 immediately after impact due to the inelastic collision. The change in potential energy is calculated by comparing the potential energy before the impact and after the pile has stopped moving.
dansbr
1. a pile driver of mass 250kg is allowed to fall from rest through a distance of 2m on to a 400kg steel pile to drive it into the ground. Each impact drives the pile into the ground by 150mm. assuming that the pile driver remains in contact with the pile after impact and that momentum is conserved, calculate

the kinetic energy of the driver and pile after impact
the change in potential energy of the driver and pile combination on moving into the ground.

2. ke=0.5mv^2
pe=mgh

3. for the first one i thought that you should add the kinetic energy of the pile driver and pile, but wouldn't the velocity be 0 after impact.

for the second question would you calculate the PE of the pile and driver before impact and after impact and it would be the difference of the two.

can someone tell me if am correct

hi dansbr!
dansbr said:
calculate

the kinetic energy of the driver and pile after impact

3. for the first one i thought that you should add the kinetic energy of the pile driver and pile, but wouldn't the velocity be 0 after impact.

no, the question means immediately after impact

(it's a perfectly inelastic collision, so a lot of energy is lost on the impact)
for the second question would you calculate the PE of the pile and driver before impact and after impact and it would be the difference of the two.

not before and after impact, but before impact and after stopping

## 1. What is a pile driver?

A pile driver is a heavy machine used in construction to drive large and heavy objects such as piles or poles into the ground. It is typically used in building foundations or in the construction of bridges, piers, and other structures.

## 2. How does a pile driver work?

A pile driver works by using a large weight, typically a heavy hammer, to repeatedly drop or drive into the top of the pile. This force creates kinetic energy which is transferred to the pile, driving it into the ground. The process is repeated until the desired depth is reached.

## 3. What is kinetic energy?

Kinetic energy is the energy an object possesses due to its motion. In the case of a pile driver, the kinetic energy is created by the falling hammer, which is then transferred to the pile, causing it to move and penetrate into the ground.

## 4. What is potential energy?

Potential energy is the energy an object has due to its position or state. In the case of a pile driver, the potential energy is stored in the weight of the hammer when it is lifted to a certain height before being dropped. This potential energy is converted into kinetic energy when the hammer falls and drives the pile into the ground.

## 5. What is the relationship between kinetic energy and potential energy in a pile driver?

The relationship between kinetic energy and potential energy in a pile driver is that the potential energy of the hammer is converted into kinetic energy when it falls, which is then transferred to the pile, causing it to move and create potential energy in the ground. This cycle continues until the pile reaches a stable position, with a balance between its potential and kinetic energy.

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