# JEE Physics Kinematics

## Kinematics PDF Notes, Important Questions and Synopsis

**SYNOPSIS**

- For motion in a straight line, the position to the right of the origin is taken as positive and that to the left of the origin is taken as negative.
- A body in straight line motion can have the line of path as vertical, horizontal or slanted.
- Path length is defined as the total length of the path traversed by an object.
**Distance:**Total path length covered during a given time interval.**Displacement:**Shortest straight line distance between the initial and final position.- Path length is greater or equal to the magnitude of the displacement between the same points.
- An object is said to be in uniform motion in a straight line if its displacement is equal in equal intervals of time. Otherwise, the motion is said to be non-uniform.
**Average speed:**Total distance travelled divided by the total time taken.**Average velocity:**Total displacement divided by the total time taken.- The average speed of an object is greater or equal to the magnitude of the average velocity over a given time interval.
- The slope of the x–t graph gives the velocity at a given instant.
- The position–time graph of a body in non-uniform motion is curved.
- The velocity–time graph of a body in non-uniform accelerated motion is curved.
- The slope of a v–t graph gives the acceleration at that instant.
- The area between the v–t graph and the time axis gives displacement.
- The steepness of the slope of the position–time graph gives us the magnitude of the velocity and its sign indicates the direction of the velocity.
- If the tangent to the position–time curve slopes upward to the right on the graph, then the velocity is positive.
- If the tangent to the position–time graph slopes downward to the right, then the velocity is negative.
- For one-dimensional motion, the slope of the velocity–time graph at a time gives the acceleration of the object at that time.
- A projectile is an object on which the only force acting is gravity.
- Projectile motion can be thought of as two separate simultaneously occurring components of motion along the vertical and horizontal directions.
- During a projectile’s flight, its horizontal acceleration is zero and its vertical acceleration is −9.8 m/s
^{2}. - The trajectory of a particle in projectile motion is parabolic.
- When a body P moves relative to a body B and B moves relative to A, the velocity of P relative to A is the velocity of P relative to B + velocity of P relative to A.

- Motion of a boat in a stream

Let velocities of boat (A) and stream (B) be and , respectively, with respect to the ground.

The velocity of boat (A) with respect to stream (B) is

Resultant velocity

Time to cross the stream

Shortest interval to cross the stream

Time is minimum when the denominator is maximum, so at , the time to cross the stream is minimum.

## Videos

- Which One of the Following is Not Correct A. The Momentum is always conserved in Elastic Collision B. The Momentum is Always conserved in Non elastic Collision C. The Momentum is always conserved for Impulsive force acting On system D The Momentum of one body system under gravity is not conserved in Y Direction
- Two particles having mass ratio n : 1 are interconnected by a light inextensible string that passes over a smooth pulley. If the system is released, then the acceleration of the centre of mass of the system is
- A cylindrical block of mass m and height h floats vertically in a liquid which is twice as dense as the block, as shown in the figure. A uniform rod of mass m/2 and length I is hinged to axis of the cylinder at A and to the wall of the vessel at B. The rod can rotate freely about point B. It is observed that the rod is horizontal in its equilibrium position. Angular frequency of small vertical oscillations of the cylinder will be m/2 B 12g V 7h
- A train of mass 16800 Kg is pulled by its locomotive with a force of 10000 N and its speed increases from 10 ms-1 to 12 ms-1 in a distance of 50 m. Calculate the resistive force assumed constant in that distance.
- A tube of mass 2m and radius 'R' is kept on smooth horizontal surface. A small sphere of mass m kept inside tube is imparted velocity v_{0} along y axis as shown in figure. The sphere just fits into the tube. Motion of particle and tube take place in horizontal plane and there is no friction at any contact. Then, speed of particle when it reaches point B is
- velocity vs displacement graph represents what?
- In a eliptical planetary motion, the velocity of a planet changes continously so as to keep the angular momentum conserved. So can we can that the planet also has a tangential acceleration while orbiting? If yes then in a 1998 JEE PYQ, (attached), the answer was (a). How????? Please explain
- Find the total distance travelled in minimum time taken by car that starts from rest and comes to rest after achieying a peak velocity of 16m/s while moving along a straight line.The magnitude of maximum acceleration and maximum retardation is same at 2m/s^(2).
- position of a particle moving in a straight line given by y= 3t^3+3t^2+5 then find acceleration of the particle at Time t=2s
- (x-t)graph

### Kindly Sign up for a personalised experience

- Ask Study Doubts
- Sample Papers
- Past Year Papers
- Textbook Solutions

#### Sign Up

#### Verify mobile number

Enter the OTP sent to your number

Change