Physics Help, Could someone check my work test coming up soon

In summary: Yes, that is the correct answer for #3. For #2, the blue side is incorrect because it uses the wrong equation. The correct equation for finding work is W = F*d*cosθ, where θ is the angle between the force and displacement. So the correct calculation would be (7.35N)(1.50m)(cos(90°))=0 J. This means that no work was required to lift the frame because the force and displacement were perpendicular.
  • #1
Ion1776
37
0
1. A parent pushes a baby stroller from home to daycare along a level road with a force of 38 N directed at an angle of 30° below the horizontal. If daycare is 0.83 km from home, how much work is done by the parent?

(38N)(cos(-30))(.83km)=27.21 J

2. You have a 0.750 kg picture frame on a mantle 1.50 m high. How much work was required to lift the frame from the ground to the mantle?

0.750*9.80=7.35N(1.50)=11.025 J

3. You lower a 2.50 kg textbook (remember when textbooks used to be made out of paper instead of being digital?) from a height of 1.81 m to 1.50 m. What is its change in potential energy?

1.81-1.50=.31
(2.50kg)(9.80)(.31)

=7.60 J

Please if someone could confirm these by working them out, please be sure of the answer before responding, Thanks so much
 
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  • #2
In 1, a Joule is a Newton meter. So check your units...

In 2, you are loose with your one "equation". The LHS does not equal the middle, but it looks like you got the right answer anyway. You should show all terms and units on each side of your equation.

3 looks okay.
 
  • #3
On #1 Should .83 Km be 830 meters, if that is the case will it make the question correct.

(38N)(cos(-30))(830m)= 27309.4568 J?
 
  • #4
Need multiple opinions on these physics problems

1. A parent pushes a baby stroller from home to daycare along a level road with a force of 38 N directed at an angle of 30° below the horizontal. If daycare is 0.83 km from home, how much work is done by the parent?

(38N)(cos(-30))(830m)=7309.4568 J?

2. You have a 0.750 kg picture frame on a mantle 1.50 m high. How much work was required to lift the frame from the ground to the mantle?

0.750*9.80=7.35N(1.50)=11.025 J

3. You lower a 2.50 kg textbook (remember when textbooks used to be made out of paper instead of being digital?) from a height of 1.81 m to 1.50 m. What is its change in potential energy?

1.81-1.50=.31
(2.50kg)(9.80)(.31)

=7.60 J

Please if someone could confirm these by working them out, please be sure of the answer before responding, Thanks so much
 
  • #5


Ion1776 said:
1. A parent pushes a baby stroller from home to daycare along a level road with a force of 38 N directed at an angle of 30° below the horizontal. If daycare is 0.83 km from home, how much work is done by the parent?

(38N)(cos(-30))(830m)=7309.4568 J?
The left hand side is correct, but the right hand side is wrong. You might want to check that you punched the numbers into your calculator correctly
Ion1776 said:
2. You have a 0.750 kg picture frame on a mantle 1.50 m high. How much work was required to lift the frame from the ground to the mantle?

0.750*9.80=7.35N(1.50)=11.025 J
The orange part is correct. You should note that the blue part is not equal to the orange part, so it is incorrect to state that they are.

Ion1776 said:
3. You lower a 2.50 kg textbook (remember when textbooks used to be made out of paper instead of being digital?) from a height of 1.81 m to 1.50 m. What is its change in potential energy?

1.81-1.50=.31
(2.50kg)(9.80)(.31)

=7.60 J
Has the textbook gained, or lost potential energy?
 
  • #6


are the answers correct for 2 and 3?

On 2 what to with the blue side

lost potential energy on 3 right?
 
  • #7


The answer to 3 is incorrect. ΔU = mgΔh, where Δh is the change in height, i.e. final value minus initial value.
 
  • #8


So should the answer be (2.50)(9.80)(-.31)=-7.595
 
  • #9
(Two threads with the same questions merged into one...)
 
  • #10
So should the answer be (2.50)(9.80)(-.31)=-7.595 FOR #3
 

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A physics test may cover topics such as mechanics, electricity and magnetism, thermodynamics, optics, and modern physics.

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To prepare for a physics test, it is important to review your notes, textbook, and any other study materials provided by your instructor. Practice solving problems and make sure you understand the concepts behind them. You can also review previous quizzes or tests to identify any areas where you may need extra practice.

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4. What should I do if I don't understand a concept in physics?

If you are struggling to understand a concept in physics, don't hesitate to reach out to your instructor for clarification. You can also seek help from a tutor, study group, or online resources. It is important to address any confusion as soon as possible to prevent it from affecting your performance on the test.

5. How can I check my work to ensure accuracy?

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