# Search results for query: *

1. ### Velocity of a piston in a piston-shaft mechanism

If ##\frac{d\theta}{dt} = 0## and ##\omega## is nonzero, will the piston move? What do you think? Drawing diagrams may help.
2. ### Velocity of a piston in a piston-shaft mechanism

Why didn't you consider ##\omega## in your solution?
3. ### Velocity of a piston in a piston-shaft mechanism

You forgot to upload the figure.
4. ### Relativistic Addition of Velocities

Yes, you're correct.
5. ### Question about an image charge problem

If you know how to set mirror charges for grounded conducting plane and sphere, this picture is enough hint for you.
6. ### Question about an image charge problem

I guess the boundary is like this in 3D, right? : Do you know how to set up image charge for grounded conducting plane and for grounded conducting sphere?
7. ### Help understanding answers: kinetic friction

Calculate the net force in terms of mass and coefficient of friction.
8. ### Help understanding answers: kinetic friction

Yes, it was straight forward. I thought the figure might contain some important information. Well, now tell me what is the net force on the object.
9. ### Help understanding answers: kinetic friction

You forgot to upload the figure.
10. ### Gravitational potential energy

Potential energy, $$U_{total}= m_{total} \cdot g\cdot h_{center~of~mass}$$ Or you can calculate the height for the two masses separately, then calculate their respective potential energy and add them.
11. ### Projectile motion on inclined plane

You misinterpreted the question. The ball moves "within" the slopes plane, I mean, it does not go "above" the plane.

Exactly!
13. ### Roller-coaster problem

Oh, sorry! I missed the line. If the passenger hold on to something, he does not need to have any velocity at the top of the loop to not fall out. At the ground level, he just needs to have kinetic energy = mass * g * height of the top of the loop The problem we have solved earlier is for the...
14. ### Roller-coaster problem

Exactly! :thumbup:
15. ### Physical interpretation of free body force diagram

The person is pushing the surface (in the direction perpendicular to the surface). That is why the surface is exerting equal normal reaction force on the person in the opposite direction.
16. ### Roller-coaster problem

You have forgot to consider the potential energy term.
17. ### I with the free vibration of bar problem

According to the rules of the forum, you have to show your attempt at a solution.
18. ### Roller-coaster problem

The velocity you have calculated is the minimum required speed 'at the top of the loop'. Are the speeds at the ground level and the top level equal? [Hints: Use energy conservation.]

I think the maximum tension in B is the tension in A minus ##mg##.

Will the mass be accelarated? Won't the rope break if the force exceeds the limit of 50N?

I am confused about how the force will be transmitted.

Won't rope B break?

Then I guess the mass is negligible.

The mass was not given in the problem.

Homework Statement [/B] A body is connected at the middle with two different ropes as in the figure. The maximum force that rope A can resist is 60 N, and for rope B its 50 N. What will happen if someone apply a downward force at the loose end of rope B, a) gradually b) very fast Homework...
26. ### Determining shortest possible "time" to reach destination

Oh, sorry. I misunderstood it.
27. ### Determining shortest possible "time" to reach destination

Thanks for your suggestion. This thought was really interesting. But, I think the pursuit curve problem does not deal with "minimum time" to catch the pursuee.
28. ### Determining shortest possible "time" to reach destination

Oh, yeah, it does. But is there any simple logic behind this fact?
29. ### Determining shortest possible "time" to reach destination

Thanks for your suggestion. But I would like to understand the logic behind the fact that the time would be optimal for the straight path.
30. ### Determining shortest possible "time" to reach destination

I solved in that way and the result matches. But I cannot quite convince myself that the resultant velocity should be in the direction of AC for minimum time. My confusion is that the magnitude of velocity can be higher for other trajectory than this shortest (in terms of length) path.
31. ### Determining shortest possible "time" to reach destination

Thanks for your reply. I took the x-axis in the direction of AB, and the y-axis is perpendicular to it. I calculated the time, ##t = \int_0^{x_1} \frac{1+y'^2}{v_r y' + \sqrt{v_b^2 - v_r^2 + v_b^2 y'^2}} \,dx## [where, ##x_1 = 8~ miles##, ##v_r = speed~ of~ river = 4 ~mi/hr## and ##v_b =...
32. ### Determining shortest possible "time" to reach destination

Homework Statement Two towns A and B, are situated directly opposite to each other on the banks of a river whose width is 8 miles and which flows at speed of 4 mi/hr. A man located at A wishes to reach town C which is 6 miles upstream from and on the same side of the river as town B. If his...
33. ### Problem on optics

I have got the answer. :)
34. ### Problem on optics

Homework Statement Light falls on the surface AB of a rectangular slab from air. Determine the smallest refractive index n that the material of the slab can have so that all incident light emerges from the opposite face CD. Homework Equations The Attempt at a Solution Let's think about this...
35. ### Rinkel's modification of Ruchhardt's method

Here is the question:
36. ### Rinkel's modification of Ruchhardt's method

Homework Statement In Ruchhardt’s method of measuring ##\gamma##, illustrated in Fig. 12.2, a ball of mass ##m## is placed snugly inside a tube (cross-sectional area ##A##) connected to a container of gas (volume ##V##). The pressure ##p## of the gas inside the container is slightly greater...
37. ### Finding value of constants of quadric equation by experiment

Homework Statement Suppose, the following equation describes the relation between an independent and a dependent variable physical quantities(that will be measured by experiments; for example, temperature, current, voltage etc) x & y : ##y = ax^2 + bx + c## We have to find the values of the...
38. ### Energy conservation and periodic motion

I solved this problem using this technique. Thanks for your help.
39. ### Energy conservation and periodic motion

Oh! Sorry! How could I make such a silly mistake!:)) Thanks for your help.
40. ### Energy conservation and periodic motion

x is the expansion of the spring.
41. ### Energy conservation and periodic motion

Homework Statement Four weightless rods of length ##l## each are connected by hinged joints and form a rhomb (Fig. 48). A hinge A is fixed, and a load is suspended to a hinge C. Hinges D and B are connected by a weightless spring of length ##1.5l## in the undeformed state. In equilibrium, the...
42. ### Time-varying refractive index

No spatial variation.
43. ### Time-varying refractive index

Homework Statement Suppose, light is passing through a liquid whose refractive index is time-varying. What will be the path of light ray ? Will it be a straaight line or curve ? Homework Equations The Attempt at a Solution I think, it will be a straight line.
44. ### Problem on a mass-spring system

So, it is, I think: for ##m_1## : ##F-T = m_1 a_1## for ##m_2## : ##T = m_2 a_2## the tension on the spring is ##T## ;
45. ### Problem on a mass-spring system

I thought, the force will be applied on the whole system, then , ##a = F/(m_1 + m_2)##
46. ### Problem on a mass-spring system

Homework Statement Suppose the surface is completely frictionless. Will the spring experience any length change?[/B] Homework Equations The Attempt at a Solution To change the length of the spring, force should be applied from both ends. In this case, there is no force of friction. So, my...
47. ### Applying law of momentum conservation

I think, after collision, the rod will have two type of motion: translational and rotational. Let, the final translational velocity of the rod be ##v_1## and final velocity of ball D be ##v_2## ; and final angular velocity of rod be ##\omega_1## ; So, applying the law of (linear) momentum...
48. ### Applying law of momentum conservation

That's good! Now, what would happen if the center was not fixed?
49. ### Applying law of momentum conservation

In the actual problem, the picture was in the vertical plane. The ball D was falling down with the accelaration of ##9.8 ms^{-2}##. So, in this case, I think, there will be a torque because of collision and another torque which is equal to ##MgR##. Is it so?
50. ### Applying law of momentum conservation

So, I think the equation will be, ## 2m \omega r^2 + Mvr = 2m \omega _f r^2 + Mv_f r## And the equation for energy conservation, ##2\cdot \frac {1}{2} m r^2 \omega ^2+ \frac{1}{2} Mv^2 = 2\cdot \frac {1}{2} m r^2\omega _f ^2 + \frac{1}{2} Mv_f ^2 ##