Motion : Revision in One shot

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ABHISHEK K RB.Tech - Aerospace, Alliance UniversityCBSE Expert | Inventor of RocketPro6+ Years Teaching Exp | Mentored more than 5000 studentsHelped 1000s of students get 10 CGPA in CBSE X

Motion : Revision in One shot

2020 Playlist

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TIO

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Distance & Displacement

Acceleration & its numericals

Average speed & Average Velocity

Graph based numericals

Distance & Velocity Time Graph

Graphical Derivations of Equations of motion

Change in Position

The total distance is calculated by measuring the total path/length covered by the object.

Displacement is calculating by the difference between initial and final position

Distance and Displacement

Distance and Displacement

Path Dependency

OInitial Position

6 m

8 m

BFinal Position

10 m

Path Dependency

Distance is path independent and displacement is path dependent.

OInitial Position

6 m

8 m

BFinal Position

10 m

Direction Dependency

Distance is Scalar. Displacement is Vector.

Direction Dependency

Q1. A man lives at A, and has to reach C. He decided to stop by and meet his friend who lives at B. So he chooses the path A-B-C. Calculate distance and displacement.

Distance 8 Km Displacement 4 Km

Distance 12 KmDisplacement 12Km

Distance 12 KmDisplacement 0 Km


A B

C D


Distance 8 Km Displacement 4 Km

Distance 12 KmDisplacement 12Km



A B

C D


Measuring Motion

Speed is the distance covered by an object per unit time .

SI unit of speed is m/s.

Speed is a Scalar Quantity.

Speed =distance

time

Velocity is defined by displacement per unit time or rate of change of displacement

SI unit of velocity is m/s.

Velocity is a Vector Quantity.

Velocity =displacement

time

Types of Motion

Uniform Motion

Types of Motion

Uniform Motion

Equal distances in equal intervals of time.

Types of Motion

Uniform Motion

Equal distances in equal intervals of time.

Non-Uniform Motion

Unequal distances in equal intervals of time.

10 s 5 s

15 s 20 s

A B

C D

Q2. Calculate the time taken by an object moving at a speed of 20 m/s, to cover a distance of 100 m.

10 s 5 s

15 s 20 s

A B

C D


5 m/s from B to A3 m/s from A to B

10m/s from A to B 10 m/s from B to A

A B

C D

Q3. A person travel from A to B along a straight line in 5 min, distance between A & B is 3 km, find velocity of the person.

5 m/s from B to A3 m/s from A to B

10m/s from A to B 10 m/s from B to A

A B

C D


Average speed: Total distance covered by an object in an interval of time.

Average Speed =total distance covered by the object

total time taken

Average Velocity: Total displacement divided by total time of motion

Average Velocity =total displacement

total time taken

Avg speed = 1.2 m/sAvg velocity = 3.2 m/s

Avg speed = 0Avg velocity = 0

Avg Speed =2.8m/sAvg velocity = 0

Avg speed =2.8 m/sAvg velocity = 1.5 m/s

A B

C D

Q4. A runner is running along a rectangular track with length 50 m and width 20 m. He travels around the track twice, finally running back to starting point. If the total time he takes to run around the track is 100 s, determine average speed and average velocity

Q4. A runner is running along a rectangular track with length 50 m and width 20 m. He travels around the track twice, finally running back to starting point.If the total time he takes to run around the track is 100 s, determine average speed and average velocity

SOLUTION

Avg speed = 1.2 m/sAvg velocity = 3.2 m/s

Avg speed = 0Avg velocity = 0

Avg Speed =2.8m/sAvg velocity = 0

Avg speed =2.8 m/sAvg velocity = 1.5 m/s

A B

C D

Q4. A runner is running along a rectangular track with length 50 m and width 20 m. He travels around the track twice, finally running back to starting point.If the total time he takes to run around the track is 100 s, determine average speed and average velocity

(i) 21 Km/hr(ii) 15 Km/hr

(i) 20 Km/hr(ii)21 Km/hr



A B

C D

Q5. Shyam travels towards south 120 km in 5 hours & then 90 km towards east in next 5 hours find his (i) average speed (ii) average velocity?





A B

C D


Acceleration : Rate of change of velocity

Acceleration =Change in velocity

time taken

SI unit of acceleration is m/s2

Acceleration : Rate of change of velocity

Acceleration =Change in velocity

time taken

SI unit of acceleration is m/s2

It is also a Vector Quantity.

Positive Acceleration: The acceleration is positive when final velocity is greater than initial velocity.

Negative Acceleration: The acceleration is negative when final velocity is less than initial velocity.

80 m/s240 m/s2

120 m/s2 160 m/s2

A B

C D

Q6. A ball hits a wall horizontally at 10m/s. It rebounds horizontally at 6m/s. The ball is in contact with the wall for 0.2s. What is the acceleration of the ball?

80 m/s240 m/s2

120 m/s2 160 m/s2

A B

C D


Graphical Representation of

Motion

Distance -Time graph

Straight line graph represents uniform motion

Curved line graph represents non-uniform motion

Distance -Time graphs

Q7. Four cars A, B, C and D are moving on a levelled road. Their distance versus time graphs are shown. Which statement is correct.

Car B is the slowest

Car A is faster than Car D

Car D is faster than car C

Car C is the slowest

A B

C D

Q7. Four cars A, B, C and D are moving on a levelled road. Their distance versus time graphs are shown. Which statement is correct.

Straight line parallel to Y axis

Straight line parallel to x axis

Straight line inclined to the time axis

Curved line

A B

C D

Q8. For a body performing motion with uniform speed, the distance-time graph is

Velocity -Time graph

Slope of the Velocity Time graph gives acceleration

Non Uniform Motion with Constant Acceleration

Uniform Motion / Zero acceleration

In any motion (uniform or non-uniform), area under velocity time graph represents displacement.

Q9. Find out acceleration and displacement respectively for below given graph from A to B

1.8 m/s2, 37.5 m 1.8 m/s2, 22.5 m

3.6 m/s2, 37.5 m 3.6 m/s2, 45 m

A B

C D


Positive Zero

Negative Variable

A B

C D

Q10. If the velocity-time graph of an object is not a straight line, then its acceleration is

Equations of Motion

The Problems which you Face!

Doubts?


Doubts?


Notes?

Tests & Assignments?

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Notes?


Competitive Exams?

Doubts?


Notes?


Competitive Exams?

Choice of Schedule?

Doubts?


Notes?


Competitive Exams?

Choice of Language?

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Doubts!

Problems SOLVED!

Notes!

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Per Class Price ₹ 2294 /- ₹ 5949 /- ₹ 9774 /-

200 600 1200

Per Class Price ₹ 11.47 /- ₹ 9.19 /- ₹ 8.145 /-

(Ya I know Decimals!!)

Lesser than Your

Equations of Motion

Let us get equations from this velocity-time graph.

Derivation 1

Derivation 2

Derivation 3

● Three equations of motions are○ v = u + at○ s = ut + ½ at2 ○ v2—u2 = 2as

● Three equations of motions are○ v = u + at○ s = ut + ½ at2 ○ v2—u2 = 2as

● These equations of motion are applicable for motion with constant acceleration.

40 s30 s

42 s 50 s

A B

C D

Q11. A person started his motion with a velocity of 15 m/s. If his velocity decreases at a constant rate of 0.5 m/s2, find out the time taken by him to come to rest.

40 s30 s

42 s 50 s

A B

C D


240 m180 m

200 m 100 m

A B

C D

Q12. A person is standing at the top of a building. He is holding a ball in his hand and dropped it from top of the building. If acceleration in the direction of motion is 10 m/s2 and time taken by ball to reach the ground is 6 seconds, find the height of the building.

240 m180 m

200 m 100 m

A B

C D


- 56 m/s256 m/s2

-128 m/s2 128 m/s2

A B

C D

Q13. A person is driving a car in a straight line with an initial velocity of 4 m/sec and an acceleration of 0.2 m/s2. After two minutes he applied brakes and car stopped after travelling 7 meters. Find out the acceleration during braking.

- 56 m/s256 m/s2

-128 m/s2 128 m/s2

A B

C D


Uniform Circular Motion

Uniform Circular Motion

When an object travels in a circular path with constant speed, this type of motion is called uniform circular motion.

Velocity of the object changes at every point as direction of motion is changing.

11 s7 s

14 s 44 s

A B

C D

Q14. A person is travelling on a circular ground with uniform circular motion. If radius of the ground is 42 m and he is running with a constant speed of 6 m/s then find out the time taken by him to complete one full round of the ground.

11 s7 s

14 s 44 s

A B

C D


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Motion : Revision in One shot

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