Work energy principle and power

Click For Summary

Discussion Overview

The discussion revolves around a physics problem involving the work-energy principle and the calculation of the speed of a box sliding down a ramp. Participants explore the application of conservation of energy, specifically focusing on gravitational potential energy (GPE) and kinetic energy (KE). The context includes a request for help in solving a homework problem.

Discussion Character

  • Homework-related, Mathematical reasoning, Technical explanation

Main Points Raised

  • A participant presents a problem involving a box sliding down a ramp and requests assistance in finding the speed at the bottom.
  • Another participant suggests applying conservation of energy, prompting questions about the initial gravitational energy and final kinetic energy.
  • One participant states that the increase in kinetic energy equals the loss of gravitational potential energy, providing the equation 1/2mv^2 = mgh.
  • There is a reiteration of the conservation of energy approach, with a request for clarification on solving the problem.
  • Another participant confirms the correctness of the equation and suggests filling in values for gravitational acceleration (g) and height (h), noting that mass (m) can be canceled from both sides.
  • A participant concludes with a calculation, stating that with h = 0.2m, the speed v = 2m/s, while expressing confusion about the ramp's length.

Areas of Agreement / Disagreement

Participants generally agree on the application of the conservation of energy principle, but there is some confusion regarding the specifics of the problem, particularly the relationship between the ramp's length and the speed calculation.

Contextual Notes

Some assumptions about the ramp's smoothness and the absence of friction are implied but not explicitly stated. The discussion does not resolve the potential confusion regarding the ramp's length and its effect on the speed calculation.

Shah 72
MHB
Messages
274
Reaction score
0
A box slides down a smooth ramp. The height of the ramp is 20cm and the length of the ramp is 2.5m. The box starts from rest. What is the speed of the box when it reaches the bottom of the ramp?
I don't understand how to solve this. Pls help
 
Mathematics news on Phys.org
We can apply conservation of energy.

What is the energy due to gravity at the beginning?
What is the kinetic energy at the end?
 
Increase in KE= loss of GPE
1/2mv^2= mgh
So gpe at the top = m×10× 0.2
GPE at the bottom = 0J
 
Klaas van Aarsen said:
We can apply conservation of energy.

What is the energy due to gravity at the beginning?
What is the kinetic energy at the end?
I don't understand how to solve this. Pls help
 
You have the correct equation.
Fill in g and h.
And we can cancel m from both sides.
 
Klaas van Aarsen said:
You have the correct equation.
Fill in g and h.
And we can cancel m from both sides.
h=0.2m, so v= 2m/s. I was getting confused with the length of the ramp.
Thanks a lottt!
 

Similar threads

  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 1 ·
Replies
1
Views
948
  • · Replies 16 ·
Replies
16
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 4 ·
Replies
4
Views
1K
  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 2 ·
Replies
2
Views
871