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JEE · NEET Physics

Class 11 · Chapter 3

Kinematics

Overview, notes, short notes, formula sheet, daily practice problems, previous year questions, and videos for this chapter — all in one place.

Kinematics JEE Notes

5 min read

Fully worked, multi-step kinematics problems — river-boat crossings, rain-man relative velocity, projectiles on inclined planes, and two-body meeting problems — the combined setups JEE Main and JEE Advanced favour, a level beyond the regular DPP.

Illustration 1 — River-Boat Problem: Shortest TIME to Cross

A boat can row at 10 km/h in still water. A river 2 km wide flows at 6 km/h. Find the minimum time to cross the river (not necessarily landing directly opposite), and the drift downstream in that time.

Illustration 2 — Rain-Man Relative Velocity

Rain falls vertically downward at 10 m/s. A man walks horizontally at 10√3 m/s. Find the velocity of the rain as observed by the man (magnitude and direction).

Illustration 3 — Projectile Range on an Inclined Plane

A particle is projected with speed 20 m/s at 60° to the horizontal, up a plane inclined at 30° to the horizontal. Find the range measured along the incline. (g = 10 m/s²)

Illustration 4 — Two Bodies Meeting Mid-Air

A stone is dropped from rest from a height of 60 m at the same instant a ball is thrown straight up from the ground below it with speed 20 m/s. Find the time and height at which they meet. (g = 10 m/s²)

Illustration 5 — Displacement from a Trapezoidal Velocity-Time Graph

A particle accelerates uniformly from rest to 20 m/s in 4 s, moves at that constant speed for 3 s, then decelerates uniformly to rest in 2 s. Find the total displacement.

Illustration 6 — Complementary Projection Angles, Heights Compared

A projectile is launched with speed 20 m/s, once at 30° and once at 60° (complementary angles, giving equal range). Find the ratio of the maximum heights reached in the two cases. (g = 10 m/s²)

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