Nonconservative forces

J. The car will have that much kinetic energy at the bottom of the driveway.In summary, the conversation discusses the problem of finding the speed of a car at the bottom of a sloped driveway with a weight of 2100 kg and an average friction force of 4000 N. It is suggested to use Newton's law of F_total = m*a to solve the problem, while another suggests calculating the gravitational force and Fx. The conversation also mentions the importance of considering the 20 degree slope and the use of energy in solving the problem.
  • #1
imaqueen
I am really having a hard time with this there is something I am missing can someone help
a 2100 kg car starts from rest at the top of a 5.0 m long driveway that is sloped at 20 Deg with the horizontal . if an average friction force of 4000 N impedes the motion find the speed of the car at the bottom of the driveway. The answer is 3.8m/s
 
Physics news on Phys.org
  • #2
Use Newton's law F_total = m*a.

JMD
 
  • #3
That's not entirely correct nbo10, first u need to calculate the Gravitational force on the truck, then you calculate the Fx, which will help you further.

p.s. don't forget the 20 degrees
 
Last edited:
  • #4
Originally posted by Astrophysics
That's not entirely correct nbo10, first u need to calculate the Gravitational force on the truck, then you calculate the Fx, which will help you further.

p.s. don't forget the 20 degrees

No, I'm entirely correct. F_total includes gravitational foce and friction.

JMD
 
  • #5
I think, I think more like a physics teacher, since I don't think F_total = m*a is very precise. I think emaqueen already knew about this equation.
 
  • #6
I'm puzzled by that. I will admit that I'm NOT a physics teacher so perhaps I don't think like one. But in a problem that talks about forces and asks for speed, I would think that F= ma would be key.


Perhaps you mean that we should do it by calculating the energy!
Okay, that's often a good way to do these problems. Initially, the car has 0 kinetic energy. Since the driveway is 5m long and sloped at 20 degrees, the height of the car at the top of the driveway is 5 sin(20)= 1.71 m and its potential energy is (2100)(9.8)(1.71)=
 

What are nonconservative forces?

Nonconservative forces are forces that do not follow the law of conservation of mechanical energy. These forces can change the mechanical energy of a system by either increasing or decreasing it.

What are some examples of nonconservative forces?

Examples of nonconservative forces include friction, air resistance, and tension in a rope. These forces dissipate energy and do not conserve it.

How do nonconservative forces affect mechanical energy?

Nonconservative forces can either increase or decrease the mechanical energy of a system. When work is done by these forces, the system's mechanical energy decreases. When work is done on the system by these forces, the mechanical energy increases.

Can nonconservative forces be conservative?

No, by definition, nonconservative forces do not follow the law of conservation of mechanical energy. Conservative forces are the only forces that conserve mechanical energy.

How do nonconservative forces affect the motion of an object?

Nonconservative forces can either speed up or slow down the motion of an object. For example, friction can slow down the motion of a sliding object, while a force applied in the direction of motion can speed it up. These forces can also change the direction of an object's motion.

Similar threads

  • Introductory Physics Homework Help
Replies
8
Views
23K
  • Introductory Physics Homework Help
Replies
1
Views
3K
  • Introductory Physics Homework Help
Replies
4
Views
14K
  • Introductory Physics Homework Help
Replies
5
Views
3K
  • Introductory Physics Homework Help
Replies
3
Views
883
  • Introductory Physics Homework Help
Replies
3
Views
3K
  • Introductory Physics Homework Help
Replies
2
Views
2K
  • Introductory Physics Homework Help
Replies
7
Views
359
  • Introductory Physics Homework Help
Replies
18
Views
1K
  • Introductory Physics Homework Help
Replies
8
Views
2K
Back
Top