# Questions tagged [homework-and-exercises]

Applies to questions of primarily educational value - not only questions that arise from actual homework assignments, but any question where it is preferable to guide the asker to the answer rather than giving it away outright. Please READ THE GUIDANCE IN META before asking homework-like questions.

16,048 questions
Filter by
Sorted by
Tagged with
1answer
59 views

### Solid in Liquid Heat Transfer (Temperatures/Entropy Changes)

Suppose we have a solid of temperature $T_s$ and heat capacity $C_p$ submerged into a pool of water that has temperature $T_w$. If $T_s \gt T_w$ and the pressure of the isolated pool-solid system is ...
2answers
36 views

### Why can I use conservation of momentum to understand a bag getting dropped on a moving truck, if the ground provides an external force?

Please help me with this sat question from released test A toy truck with a mass of $0.6$ kg initially coasts horizontally at a speed of $2$ meters per second. A child drops a beanbag with a mass ...
1answer
63 views

2answers
34 views

### Constrained motion of the vertices of a quadrilateral

There is this square of side length $a$. It's opposite vertices are being pulled in opposite directions with a constant velocity $u$. The question here is what is the velocity of the remaining pair of ...
0answers
32 views

### Obtain an expression for pressure difference [closed]

The question is "For the two-liquid manometer, shown below, obtain an expression for $p_1 – p_2$. Let $\mathcal A$ be the area of each tank and $\mathcal S$ the area of the tube. Let $S_3$ be the ...
0answers
33 views

### From a potential energy equation, how can we determine whether or not the particle undergoes circular motion?

(I realise this may be considered a homework question but I have read the rules.) I'm working through an introductory book on classical mechanics and there is this question: Consider a particle of ...
0answers
56 views

1answer
43 views

### Particle moving on ellpse with foci as origin

I'm reading the book "An introduction to Celestial Mechanics" by Forest Ray Moulton. In the first chapter, I got stuck on the following problem: A particle moves in the ellipse whose parameter and ...
2answers
102 views

### Isn't friction on an incline coefficient of friction times the Reactional force?

Question - "As shown in figure a body of mass 1 kg is shifted from A to D on inclined planes by applying a force slowly such that the block is always in contact with the plane surfaces. ...
0answers
35 views

### Problem related to combination of lens & equivalent focal length and lens maker's formula [closed]

in between two equiconvex lens( made of glass) of focal length of 20cm there is a layer of water which also acts as a convex lens.The whole figure is surrounded by air. Find out it's equivalent focal ...
1answer
75 views

### Simple question on quantization of EM field

This is part of the lecture note of QFT by Tong: I have a question on the last part of (6.27). Why does it hold? Actually this question is not about QFT and is about just integral. The typical way to ...
1answer
26 views

### A thin rod is standing on a smooth surface [closed]

A uniform thin rod of mass m and length l is standing on a horizontal surface. A slight disturbance causes the lower end of the rod to start falling. find the velocity of the centre of mass of the rod ...
2answers
57 views