Potential energy of a block moving up and down an incline.

  • Thread starter YMMMA
  • Start date
  • #1
156
10

Homework Statement


Which graphy represents the potential energy of the block as a function of time?

Homework Equations


PE=mgh

The Attempt at a Solution


First, the potential energy is zero until it reache the top of the incline where the potential energy is maximum. Moving down, the potential energy decreases until zero. But then I am confused is it a parabolic graph like D or linear?
 

Attachments

  • 52206273-6651-4C69-BE5A-7BC246E2EA27.jpeg
    52206273-6651-4C69-BE5A-7BC246E2EA27.jpeg
    27.7 KB · Views: 552

Answers and Replies

  • #2
kuruman
Science Advisor
Homework Helper
Insights Author
Gold Member
10,129
3,257

Homework Statement


Which graphy represents the potential energy of the block as a function of time?

Homework Equations


PE=mgh

The Attempt at a Solution


First, the potential energy is zero until it reache the top of the incline where the potential energy is maximum. Moving down, the potential energy decreases until zero. But then I am confused is it a parabolic graph like D or linear?
To answer that question, you need to find U(t). Can you do that? Hint: h(t) will do because U(t) = mgh(t).
 
  • #3
156
10
To answer that question, you need to find U(t). Can you do that? Hint: h(t) will do because U(t) = mgh(t).
Ahh, right the height is proportional to the time squared. So, it’s a parabola.
 
  • #4
kuruman
Science Advisor
Homework Helper
Insights Author
Gold Member
10,129
3,257
Parabola is correct, but which one of the two shown?
 
  • #5
156
10
D. Since it starts and ends with zero.
 
  • #6
kuruman
Science Advisor
Homework Helper
Insights Author
Gold Member
10,129
3,257
D. Since it starts and ends with zero.
Not a good enough explanation. The zero value for potential energy is (as you know) arbitrary. What if the other graph was labeled so that the potential energy is zero at its end points?
 
  • #7
156
10
Not a good enough explanation. The zero value for potential energy is (as you know) arbitrary. What if the other graph was labeled so that the potential energy is zero at its end points?
No, it starts with zero, reaches maximum height/ potential energy, and then decrease to zero.
 
  • #8
kuruman
Science Advisor
Homework Helper
Insights Author
Gold Member
10,129
3,257
Right. The potential energy must exhibit a maximum and must be parabolic.
 

Related Threads on Potential energy of a block moving up and down an incline.

Replies
6
Views
2K
Replies
4
Views
16K
Replies
4
Views
2K
Replies
5
Views
19K
  • Last Post
Replies
23
Views
4K
Replies
2
Views
2K
  • Last Post
Replies
15
Views
2K
Replies
4
Views
2K
Replies
3
Views
2K
Top