Doubtify – JEE Ki Taiyaari, Simple Bhasha Mein

  🎬 Restitution ka Concept – Ekdum Easy! "Jab do objects takraate hain, to unke bounce back karne ki ability ko hi bolte hain Coefficient of Restitution!" ⚡ What is Coefficient of Restitution (e)? Formula: e = (Relative speed after collision) / (Relative speed before collision) It tells us how “bouncy” a collision is. Simple! 🧠 Important Points to Remember: 0 < e < 1 → Partially Elastic Collision (thoda bounce, thoda energy loss) e = 1 → Perfectly Elastic Collision (poora bounce, no energy loss) e = 0 → Perfectly Inelastic Collision (no bounce, objects stick together) 🧪 Real-Life Example: Let’s say a ball hits the ground : If e = 0.8 → Ball bounce karegi, par speed thodi kam hogi If e = 0 → Ball bilkul waapas nahi aayegi (stick to ground) ❗ Memory Trick (Easy Yaad Karne Ke Liye): e = After / Before Numerator = After collision Denominator = Before collision Bas itna yaad rakho! 📢 Conclusion: "Bounce kitna hoga?...

  🔬 Bulk Modulus Concept – Find Initial Volume | Doubtify JEE 📌 Question: A sample of a liquid is kept at 1 atm . It is compressed to 5 atm , which leads to a change of volume of 0.8 cm³ . If the bulk modulus of the liquid is 2 GPa , the initial volume of the liquid was ______ litre . (Take 1 atm = 10⁵ Pa) 🖼️ Question Image:

  ⚙️ A Thin Rotating Disk – Torque & Diameter Problem | Doubtify JEE 📌 Question: A thin solid disk of mass 1 kg is rotating along its diameter axis at the speed of 1800 rpm . An external torque of 25π Nm is applied for 40 seconds , increasing the speed to 2100 rpm . Find the diameter of the disk. 📸 Question Image:

🚆 Train Crossing Concept in 59 Seconds | Doubtify JEE Shorts 📌 Question: Ever wondered how long one train takes to pass another or a platform? The Train Crossing Concept helps solve such questions in seconds using speed-distance fundamentals.

  🧪 Young’s Modulus from Wire Extension | JEE Physics | Doubtify 📌 Question: A 3 m long wire of radius 3 mm shows an extension of 0.1 mm when loaded vertically by a mass of 50 kg in an experiment to determine Young's modulus. The value of Young’s modulus of the wire as per this experiment is P × 10¹¹ N/m² , where the value of P is: (Take g = 3π m/s²) 🖼️ Question Image:

     📌 Question: Water droplets are coming from an open tap at a particular rate. The spacing between a droplet observed at the 4th second after its fall to the next droplet is 34.3 m . At what rate are the droplets coming from the tap? (Take g = 9.8 m/s²) 🖼️ Question Image:

    🧲 Motion in a Plane  |  Physics |  Doubtify JEE 💡 Question: A mosquito is moving with a velocity  v = 0.5 t² î + 3t ĵ + 9 k̂ m/s and accelerating in uniform conditions. What will be the direction of motion of the mosquito after 2 seconds? 🖼️ Question Image: 🔬 Concept Overview: This is a vector motion problem where you're given a time-dependent velocity vector in three dimensions. To find the direction of motion , we must compute the velocity vector at  t = 2 t  =  2 seconds and then determine its direction using unit vector analysis or angle calculation with respect to axes. This is a key concept from the chapter "Motion in a Plane" , often asked in JEE Mains or Advanced. 🧠 Step-by-Step Explanation: Given: v ⃗ ( t ) = 0.5 t 2 i ^ + 3 t j ^ + 9 k ^ \vec{v}(t) = 0.5t^2 \hat{i} + 3t \hat{j} + 9 \hat{k} At t = 2 t = 2  seconds: i-component: 0.5 × 2 2 = 2   m/s j-component: 3 × 2 = 6   m/s 3 \times 2 = 6 \, \text{m/s} ...

🧪 Redox Reactions | Chemistry |  JEE Mains 📌 Question: Balance the equation by ion-electron method in basic medium: Zn + NO 3 − → Zn 2 + + NH 4 +​ This is a classic redox equation where zinc is oxidized and nitrate is reduced. The balancing must be done using the ion-electron method under basic medium conditions . 🖼️ Question Image: 🧠 Solution (Image): 🎥 Video Solution: 🔍 Why this Question is Important: This question is frequently asked in JEE Mains and Advanced , especially in the chapter Redox Reactions . It tests key skills like: Identifying oxidation and reduction half-reactions Using the ion-electron method properly in basic medium Applying concepts of oxidation states, electrons, and balancing H₂O/OH⁻ ions Understanding this concept is crucial for solving more advanced redox problems in competitive exams. 📩 Have a Doubt? Drop us a mail at  doubtifyqueries@gmail.com  or DM us on  Instagram . Stay consistent. Watch – Pause – Solve – Repeat. ...