Find out the average resistance of the ground, Mechanical Engineering

Find out the average resistance of the ground:

In a construction of pile-driving for building, a pile driver of mass 25 kg freely drops through a height of 3 metre on the top of a pile having mass of 50 kg. If this is driven into the ground through 7.5 cm, find out the average resistance of the ground to pile driving and the amount of energy lost in impact.

Solution

WH   =  Weight of pile-hammer (driver) = 25 × g N

VH   = Velocity of driver before impact =

                                      2413_Find out the average resistance of the ground.png = 7.67 m / sec.

WP  = Weight of pile = 50 g N.

By Using principle of conservation of the momentum,

 (WH  VH )/g = ((WH + WP )/g) Vc

where, Vc is a common velocity of the pile along with hammer

∴ Vc  = 25 × 7.67 /75 = 2.56 m / sec.

Figure 8.7

Refer Figure showing ground resistance R

2157_Find out the average resistance of the ground1.png

R′ = Net upward resistance = R - WP  - WH

                                                = R - (75 g )

∴ (R - 75 g ) × 7.5 = ( (25 + 50) × (2.56)2/2

∴ R - 75 × 9.81 =75 × (2.56)2 /15

∴ R = 768.52 N

KE lost in impact = KE before impact - KE after impact

=25 × (7.67)2 / 2 -75 × (2.56)2 /2

= 735.36 - 245.76

= 489.60 N. m.

Posted Date: 1/29/2013 7:07:00 AM | Location : United States







Related Discussions:- Find out the average resistance of the ground, Assignment Help, Ask Question on Find out the average resistance of the ground, Get Answer, Expert's Help, Find out the average resistance of the ground Discussions

Write discussion on Find out the average resistance of the ground
Your posts are moderated
Related Questions
Describe various classifications of instruments and differentiate between null type and deflection of instruments with suitable examples.


Keywords related to Air transportation: Airfield/Airport       :            The area which contains the facilities needed for the operation of aircraft. Apron

sir/madam, i would like to teach online how can i have to proceed

The National Aeronautics and Space Administration (NASA) studies the physiological effects of large accelerations on astronauts. Some of these studies use a machine known as a cent

Stress relaxation is creep related phenomenon: Problem: What is stress relaxation? Give example. Solution Stress relaxation is creep related phenomenon. It is los

procedure to draw velocity and acceleration diagram using relative velocity method

A machine of mass one tonne is acted upon by an external force of 3000 N at a frequency of 1500 rpm. To reduce the effects of vibration, isolator of rubber having a static deflecti

Q. Module Assembly Site Preparation? To set a module on the piles installed on project site, the following preparations shall be made: The Designer shall provide design elev

What is the magnitude of frictional force after perfect rolling begins and why? solution) After pure rolling begins,frictional force is 0. This is because the velocity of he c