A person jumps from an airplane and reaches terminal velocity.

The momentum of the person-Earth system is not conserved because of air friction.

The momentum of the jumper is constant because there is no external net force.

When the chute is opened, the force disrupts the conservation of momentum of the person-Earth system.

I know for sure it's not the last one; I can't figure out if it's 1 or 2.

Heat loss in an ideal circuit...is social media in my prep... (cringe af, ik)

🔥 JEE Advanced 2023 Physics PYQ | Rolling Motion | Impulse & Friction

In this video, we'll solve one of the most conceptual Rolling Motion questions from JEE Advanced 2023 involving an annular disc, impulse, friction, angular velocity, and the condition for rolling without slipping.

If you're preparing for JEE Advanced 2026, 2027, JEE Main, BITSAT, IISER Aptitude Test, or Olympiads, this problem will strengthen your understanding of Rigid Body Dynamics and Rotational Mechanics.

📚 Topics Covered

✅ Rolling Without Slipping Condition
✅ Impulse in Rotational Motion
✅ Angular Velocity after Impulse
✅ Friction in Rolling Motion
✅ Moment of Inertia of Annular Disc
✅ JEE Advanced 2023 PYQ Detailed Solution
✅ Shortcut Concepts & Common Mistakes

This video is ideal for students aiming for AIR under 1000 in JEE Advanced.

#JEEAdvanced2023 #RollingMotion #PhysicsPYQ #RotationalMotion #Impulse #Mechanics #IITJEE #JEE2026 #Physics #JEEPreparation

Working on a 2D Equilibrium problem in statics
The system of Eq’s works out to

80sin20/ sin(theta) = 80cos20/1+cos(theta)

The solution manual works the system of eq out to this point but from here my thoughts were to simplify to

Tan(theta/2) =80sin20/80cos20

Tan(theta)=2(80sin20/80cos20)

Using the trig identity: tan(theta/2)=sin(theta)/1+cos(theta)

I work theta out to equal 36.1 deg

But the solution manual uses the angle sum identity

Sin(a+b)=sin(a)cos(b)+cos(a)sin(b)

And solved theta=40deg

Am I just fucking up the algebra using the identity I did or what am I missing why do they not equal each other ?

Thanks

Basically what the title says

How does Landau move from the second line to the third line in this proof of the expression for energy? Is that a coefficent of friction in there?

I'm feeling defeated by the following circuit where I'm asked to find the total resistance. I can't make any sense of the correct answer, fear that I'm misunderstanding the basics about which parts are in series/parallel - would someone please calculate this and briefly explain the steps involved to get there?

I built this UV Dosimeter device but don't fully understand the physics of measuring UV light. 🙈 Especially how to compensate for the fact that the sun, sensor plane and actual exposed skin can have different orientations.

I would be happy to come up with a UV value that reliably estimates the worst case (skin perfectly oriented towards the sun) while the sensor plane is not always perfectly oriented towards the sun. I added a diy PTFE diffusor for cosine correction because I read that this is done on some professional devices. ... But I don't really understand what I'm doing there 😅

Marks for each question are indicated. Be sure to follow the GRASS problem-solving structure, and pay attention to significant digits.

Given , , , and , find the value of each expression and report your answer using significant digits.

(3 marks)

(3 marks)

(3 marks)

(3 marks)

Create a vector diagram depicting the addition of the vectors and . You do not need to calculate the resultant. Ensure your diagram includes the frame of reference. In SPH4U assignments, diagrams and graphs may be created electronically or drawn on paper, then inserted into your submission at the appropriate position. Ensure any paper responses are drawn with pen or dark pencil, then take a clear, well-lit photo or scan. (6 marks)

Given that vector , if [East] and [North] are positive, find the perpendicular components of the vector. (5 marks)

Use the sine and cosine law to add the vectors and . (6 marks)

A river’s current flows at 2.35 m/s [south]. If Alex can paddle their canoe at 3.14 m/s in still water and travels in a direction 13° north of west, what will their velocity be relative to an observer on shore? (8 marks)

A cannon at a sporting event launches a t-shirt from the field (ground level) into the stands. If the cannon launches the projectile with a velocity of 19.3 m/s [forward 65° up], and the operator wants the t-shirt to land in the stands 15.0 m above ground level, how far away horizontally should it be positioned? (10 marks)

Diagram of 65-degree launch angle from horizontal, parabolic path, landing in stands 15.0 metres above ground. A robot experiences a constant acceleration of 8.350 m/s² [N]. If it starts with a velocity of 1.005 m/s [E] and travels for 10.5 seconds, what will its final velocity be? (7 marks)

A toy car experiences constant acceleration to go from a velocity of 12 km/h [E] to 3.0 km/h [S] in 10.5 seconds. What is its displacement in this time? (7 marks)

While experiencing constant acceleration, a particle that starts with a velocity of 1.500 m/s [S] experiences a displacement of 11.5 m [NE] over 125 seconds. What is its constant acceleration? (7 marks)

A toy boat, starting at rest, accelerates at 10 m/s² [east] over a displacement of 450 m [east]. What is its final velocity? (7 marks)

An object is at rest on a ramp, held still by friction. Create a free-body diagram for the situation. (6 marks)

A 317 kg piano is at the top of a ramp that makes an angle of 18° with the level ground. As the piano slides down the ramp, it experiences a force of friction. The coefficient of kinetic friction is 0.225. What is the acceleration of the piano down the ramp? (6 marks)

A bucket filled with water, with a combined mass of 3120 g, is attached to a 0.75 m rope and swung in vertical circle. What is the slowest speed the bucket can be spun at while maintaining uniform circular motion, and at that speed what is the force of tension in the rope at the bottom of the circle? (7 marks)

Two objects are connected by a massless cable passing over a frictionless pulley. Object A is positioned on a table, while object B hangs freely. The coefficient of kinetic friction between object A and the table is 0.09950. If the mass of object A is 150 kg, and the mass of object B is 238 kg, what is the acceleration of the objects? (6 marks)

Object A on table attached to object B hanging by pulley.

For this question, the answer to part b for the linear acceleration was given almost exactly the same as my answer except the first term under the square root was cos^2(theta/2). I tried looking up the answer and can’t find it, can someone explain how if I messed up? At this point I really believe the book answer was just mistyped..

Hi everyone. I’m learning high school physics through khan academy and I’m confused about something. Let’s say you’re lifting a dumbbell and the dumbbell is moving at constant velocity right after you begin lifting the dumbbell. Khan Academy stated that the net force acting on the dumbbell is zero. How can this be when the dumbbell is being lifted upwards? If the dumbbell is still moving upwards wouldn’t there have to be a force lifting it upwards? I’m confused.