physicshelpline - Question of the dayphysicshelpline - Question of the dayhttps://www.physicshelpline.com/QuestionMon, 08 Jun 2026 16:55:12 +0530http://zoho.com/sites/<![CDATA[Projectile Motion]]>https://www.physicshelpline.com/Question/post/ptojectile-motion

Q- A particle is projected in a vertical plane from a point O with velocity u at angle α to the horizontal. Find the time at which the particle is moving at angle θ  to the horizontal.


]]>Fri, 05 Jun 2026 13:02:00 +0530<![CDATA[Tipping Before Sliding ]]>https://www.physicshelpline.com/Question/post/tipping-before-sliding

Q- A box of base area as a square of side 0.50 m, height of 1 m and mass 200 kg rests on horizontal floor of a truck with one edge of the base is perpendicular to direction of motion of the truck. If the acceleration of the truck is gradually increased, what is the minimum value of friction coefficient for which the box tips before it slides? 

Solution:


]]>Fri, 29 May 2026 13:02:35 +0530<![CDATA[Standing Waves]]>https://www.physicshelpline.com/Question/post/standing-waves

Q- The vibrations of a string of length 60 cm fixed at both ends are represented by the equation 

                y  = 4 sin (π x/15) cos (96 π t)  

(here x and y are in cm and t in seconds) 

(a)  What is the maximum displacement of a point at x = 5 cm? 

(b)  Where are the nodes located along the string ?

(c) What is the velocity of the particle at x = 7.5 cm and at t = 0.25 s?

(d) Write down the equations of the component waves whose superposition’s give the above wave. 

Solution:

]]>Fri, 22 May 2026 10:16:00 +0530<![CDATA[Compound Microscope ]]>https://www.physicshelpline.com/Question/post/sliding-down-the-curved-path1

Q- A compound microscope is used to enlarge an object kept at a distance 0.03m from it’s objective which consists of four thin convex lenses in contact and has focal length 0.02m. If a lens of focal length 0.1m is removed from the objective, then by what distance the eye-piece of the microscope must be moved to refocus the image?

Solution:

]]>Fri, 15 May 2026 08:55:00 +0530<![CDATA[Sliding down the curved path]]>https://www.physicshelpline.com/Question/post/sliding-down-the-curved-path

Q- A bead slides down along a frictionless stiff wire of length L which is bent in form of a serpentine coil of length L/2 and placed vertically as in figure. What is the slide time to reach the ground? The gap between the turns is much less than the length of the wire.


Solution:

]]>Tue, 12 May 2026 08:55:00 +0530<![CDATA[Surface Tension]]>https://www.physicshelpline.com/Question/post/surface-tension

Q- Two soap bubbles of radii R1 and R2 coalesce to form a double bubble as in figure. Find the radius of curvature of their common surface. 

Solution:

]]>Thu, 30 Apr 2026 10:12:11 +0530<![CDATA[Simple Harmonic Motion]]>https://www.physicshelpline.com/Question/post/simple-harmonic-motion

Q- A light platform is attached to the top end of a vertical spring of force constant K. The lower end of the spring is fixed to the ground. A small ball of mass m is dropped from height h above the platform and strikes it elastically. Find the maximum velocity and maximum acceleration of the ball after it strikes the platform. 


Solution: 

]]>Tue, 21 Apr 2026 16:07:15 +0530<![CDATA[A satellite of the Earth]]>https://www.physicshelpline.com/Question/post/a-satellite-of-the-earth

Q- A satellite of the Earth is moving in a circular orbit of radius R. By what fraction its velocity v be increased for the satellite to be in an elliptical orbit with minimum distance from the Earth equal to R and maximum distance from the Earth equal to 2R? 


Solution:

]]>Thu, 16 Apr 2026 07:46:57 +0530<![CDATA[Change in Entropy ]]>https://www.physicshelpline.com/Question/post/change-in-entropy

Q- One mole of an ideal gas is contained in a thermally insulated container that is connected to another container of equal volume that is initially evacuated. The valve connecting the two containers is now opened and the gas allowed to expand isothermally to fill both sides. The new total volume is twice original volume.

a) What is the entropy change for this process?

b) Is this process reversible or irreversible? Why? 


Solution:

]]>Fri, 10 Apr 2026 19:13:00 +0530<![CDATA[Electrostatic energy ]]>https://www.physicshelpline.com/Question/post/electrostatic-energy

Q- A point charge q is placed at each corner of a cube of edge l. Find electrostatic energy of the system of charges.


Solution:

]]>Fri, 03 Apr 2026 19:13:25 +0530