Exams Prep Master

Physics is viewed as the toughest among the three subjects of NEET. However, a good position can be considered typically when a candidate scores over 140 marks in physics for which he/she needs to attempt around 40 questions with a high accuracy rate. To score well in this segment of **NEET 2021**, students should go through the significant topics, basic definitions, and practice on sample questions mentioned in the section below.

The Physics portion carries 25% weightage in **NEET question paper** which is 180 marks. For each right answer candidates can score 4 marks, whereas, for a wrong answer, 1 mark will be deducted. The topic Planar Motion or Motion in a Plane carries 1.5% weightage of marks in NEET, with a normal of 1-2 questions. Read the article to know more in detail about definitions, formulas and solved sample questions.

## Planar Motion

Motion in a plane or Planar Motion, refers to the point where we consider motion in two dimensions as only two dimensions makes a plane. Here, we take two axes into consideration,for the above mentioned dimensions as commonly as the X-axis or Y – axes. In order to get the equation of the motion in a plane, we must know about motion in one direction or Planar Motion.

## Equations of Plane Motion

The equations of motion in a straight line or Planer Motion are:

- v = u+at
- s = ut+1/2 at²
- v2 = u² + 2as

Where,

v is final velocity of the particle

u is initial velocity of the particle

s is displacement of the particle

a is acceleration of the particle

t is the time interval in which the particle is in consideration.

In a plane, we have to apply the same equations separately in both the directions: X-axis and Y-axis. Hence,this will give us the equations for motion in a plane.

- vy = uy + ayt
- sy = uy t +1/2 ay t²
- v²y = u²y+2ay s

Here,

vy is final velocity of the particle in the y-direction

uy is initial velocity of the particle in the y-direction

sy is displacement of the particle in the y-direction

ay is acceleration of the particle in the y-direction

Similarly, for the X-axis :

- vx = ux + ax t
- sx= ux t+1/2 axt²
- v²x = u²x+2 axs

Here,

vx is final velocity of the particle in the x-direction

ux is initial velocity of the particle in the x-direction

sx is displacement of the particle in the x-direction

ax is acceleration of the particle in x-direction

**Must Read:**

## Projectile Motion: Plane Motion

One of the common examples of motion in a plane is Projectile motion. In a projectile motion, the acceleration acting is only, in the vertical direction which is acceleration due to gravity (g). Therefore,to find the unknown parameters, equations of motion can be applied separately in the X-axis and Y-axis.

Some examples of Two-Dimensional Plane Motion

- Throwing a cannonball/a ball.
- The movement of a billiard ball on the billiard table.
- The motion of a shell, fired from a gun.
- A motion of a boat in a river.
- The movement of the earth around the sun.

## Sample Questions

Question 1. Look carefully if the following algebraic operations with scalar and vector physical quantities,meaningful. If not,give reasons:

- adding any two scalars,
- adding a scalar and a vector of the same dimensions,
- multiplying any vector with a scalar,
- multiplying any two scalars,
- adding any two vectors,
- adding the vector and a component of the vector

Ans: Reasons for the following equations-

- Only when both the scaler quantities represent the same physical quantity,the addition of two scaler quantities will meaningful.
- The addition of a vector quantity and a scalar quantity is not meaningful.
- For example, force is multiplied with time to give impulse, therefore, a scaler can be multiplied with a victor.
- This equation is meaningful, because,a scalar irrespective of the physical quantity it holds,can be multiplied by another scalar having the same or different physical dimensions.
- It is meaningful because,the addition of two vector quantities,only if they both represent the same physical quantity,is possible.
- A component of a vector can be added to the same vector as they both will have the same dimensions,so it is meaningful.

Question 2: Go through the statements below and state with reasons, which of them is either true or false:

- The Vector's magnitude is always a scalar,
- Each component of a vector is always a scalar,

Ans:

- As,the magnitude of a vector is a number. Hence, it is a scalar (True).
- Each component of a vector is also a vector, so not always a scaler (False).

## Relation Between Linear and Angular Quantities

- The relation between the liner and angular quantities is represented by
- Linear velocity is
- Linear accerlartaion is
- Tengtengial accerlartaion is
- Centripetal acceleration is
- Net acceleration is

## Center of Mass of Continuous Body

It is defined by

- Center of mass about
- Center of mass about
- Center of mass about

### Law of Conservation of Linear Momentum

It can be defined as

## NEET Planar Motion Preparation Plan

The candidates should pre plan on how to proceed with the revision for the examination. Accordingly,a well refined plan is very important to begin. Follow these steps for your convenience:

**Tip 1-Check the schedule and test design:** Checking the NEET Physics Syllabus and Examination design is the absolute initial step of the planning. It is likewise important,to know about the checking plan in the Physics Section of NEET. **Check NEET Physics Preparation**

**Tip 2-Gain lucidity on significant ideas:** The main subjects, as per earlier years' papers in the Physics Section are - Mechanics, Heat and Thermodynamics, Electrodynamics and Modern Physics. You should initially explain and comprehend the ideas pertinent to these points for the examination plan. Whenever that is done, you can move onto different ideas. **Check NEET Month Wise Time Table**

**Tip 3-Know all formulae:** Formulae is the center of Physics. The most basic advance in planning for NEET Physics is learning the formulae. You can utilize a little note pad to compose all the formulae for NEET Physics. Guarantee that you test your memory on these formulae consistently.

**Tip 4-Refer to the best reference books of Physics for NEET: **You need to allude to the best material science books for NEET. NEET follows the inquiry examples of NCERT, consequently NCERR is the awesome after up.You can likewise utilize a couple of more books for careful learning and practice. **Check Best Books for NEET**

**Tip 5-Solve question papers of earlier years:** The most ideal approach to plan for NEET Physics is to settle question papers of the earlier years. Tackling these NEET Physics addresses will assist you with perceiving NEET's example of inquiries. Doing so will likewise speed up and accuracy in replying. Make a point to respond to as many inquiry papers as you can.

**Tip 6-Make notes:** You should make notes of the multitude of fundamental formulae, hypotheses and standards during your NEET Physics preparing. Physical science notes for NEET will assist you with understanding the ideas snappier, and will likewise help you plan for the latest possible time.

**Tip 7-Take online false tests:** Taking on the web mock tests will assist you with deciding how well you have read for the test. It will likewise assist you with perceiving your regions of shortcomings.

**Tip 8-Enhance the strength of your powerless regions:** Seek to reinforce your frail zones. Invest more energy on the themes that challenge you the most. You need to focus on NEET Physics' most significant themes and afterward plan for the less significant ones.

**Tip 9: Video Lecture on NEET Physics by NTA: **In request to assist understudies with setting up a test as serious as NEET, NTA has delivered content-based recordings. They have been made only for NEET-UG and JEE Mains by IIT experts or subject specialists.

## Previous Years Sample Questions on Planet Motion

Ques 1. Which one of the following statements is true?

- A scalar quantity is the one that is conserved in a process.
- A scalar quantity does not take negative values.
- A scalar quantity does not vary from one point to another in space.
- A scalar quantity possess the same value for all the observers from different orientations of axes

Ans: (d)

Ques 2. The component of a vector r along X-axis will have maximum value if

- r is along positive Y-axis
- r is along positive X-axis
- r makes angle of 45° with the X-axis
- r is along negative Y-axis

Ans:(b) as component is rcosθrcosθ as this is maximum when θθ is zero

Ques 3.Consider the quantities, pressure, power, energy, impulse, gravitational potential, electrical charge, temperature, area. Out of these, the only vector quantities are

- Impulse, pressure and area
- Impulse and area
- Area and gravitational potential
- Impulse and pressure

Ans:(b) As potential and Pressure are scalar quantities

Ques 4: If A= 3i + 4j and B= 7i + 24j. Which is of the below vector having the same magnitude as B and parallel to A

- 15i + 20j
- 15i - 20j
- 24i - 7j
- 7i - 24j

Solution:

|A|=√32+42=5|A|=32+42=5

Unit vector in the direction of A will be given by

ˆA=A|A|=15(3i+4j)A^=A|A|=15(3i+4j)

Also

|B|=√72+242=25|B|=72+242=25

The vector having the same magnitude as B and parallel to A

=|B|ˆA=25×15(3i+4j)=15i+20j=|B|A^=25×15(3i+4j)=15i+20j

Hence (a) is the correct option

Ques 5: For a particle performing uniform circular motion, choose the correct statement(s) from the following:

- Magnitude of particle velocity (speed) remains constant.
- Particle velocity remains directed perpendicular to radius vector.
- Direction of acceleration keeps changing as particle moves.
- Angular momentum is constant in magnitude but direction keeps changing

Ans:(a),(b) and (c)