Kinetic Energy and the Work-Kinetic Energy

In summary, using energy considerations, the average force exerted by a 2100-kg pile driver on a steel I-beam is calculated to be 8.78x10^5N as it falls 5.00m and drives the beam an additional 12.0 cm into the ground. This is calculated by equating the work done by the force with the potential energy lost by the pile driver.
  • #1
Joyci116
45
0

Homework Statement


A 2100-kg pile driver is used to drive a steel I-beam into the ground. The pile driver falls 5.00 m before coming into contact with the top of the beam. Then it drives the beam 12.0 cm farther into the ground as it comes to rest. Using energy considerations, calculate the average force the beam exerts on the pile driver while the pile driver is brought to rest.

m=2100 kg
Xi=5.00m
Xf=12.0 cm =.12m


Homework Equations


K=.5mV^2
U=mgh
F=ma



The Attempt at a Solution


I rearranged the formula F=ma to a=F/m. And I tried using a kinematic equation, but I have failed.
 
Physics news on Phys.org
  • #2
I think you want to equate work with potential energy

F*x = F * (.12m) = mgh = mg(5m + .12m)
 
  • #3
What I did is
Loss in energy=Loss in PE from the topmost point=mg(5.12)
Avg. Force=mg(5.12)/0.12
=8.78x10^5N
 
  • #4
That is the number I get.
 
  • #5
Thank you very much.
 

1. What is kinetic energy?

Kinetic energy is the energy an object possesses due to its motion. It is dependent on both the mass and velocity of the object, and is a scalar quantity measured in joules (J).

2. How is kinetic energy calculated?

The formula for calculating kinetic energy is KE = 1/2 * m * v^2, where m is the mass of the object and v is its velocity. This formula assumes that the object is moving in a straight line.

3. What is the relationship between kinetic energy and work?

Work is defined as the transfer of energy from one object to another. Kinetic energy is the energy an object possesses due to its motion. Therefore, work done on an object will result in a change in its kinetic energy.

4. Can an object have kinetic energy at rest?

No, an object cannot have kinetic energy at rest. Kinetic energy is dependent on an object's velocity, so an object must be in motion to have kinetic energy.

5. How does kinetic energy change in different frames of reference?

Kinetic energy is a frame-dependent quantity, meaning it can have different values depending on the observer's frame of reference. However, the overall change in kinetic energy will be the same in all frames of reference, as it is a conserved quantity.

Similar threads

Replies
1
Views
461
  • Introductory Physics Homework Help
Replies
2
Views
821
  • Introductory Physics Homework Help
Replies
4
Views
341
  • Introductory Physics Homework Help
Replies
6
Views
4K
  • Introductory Physics Homework Help
Replies
6
Views
913
  • Introductory Physics Homework Help
Replies
7
Views
819
  • Introductory Physics Homework Help
2
Replies
55
Views
1K
Replies
11
Views
959
  • Introductory Physics Homework Help
Replies
4
Views
1K
  • Introductory Physics Homework Help
Replies
6
Views
1K
Back
Top