# NCERT Class 9 Physics Formula and Important Terms Board Sample Problems Part 1

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**CBSE Class 9 Physics Summary**

This pdf lists all the Class 9 CBSE physics formula and summary in a concise manner to help the students in revision and examination as per NCERT syllabus

## Motion

S. No | Quantities | Description |

1 | Distance | It is the length of the path (the line or curve) described by an object moving through space. Distance is independent of direction. Thus, such physical quantities that do not require direction for their complete description are called scalars. |

2 | Displacement | When a body moves from one position to another the shortest distance between the initial and final position of the body along with its direction is known as displacement. Displacement has both direction and magnitude for its complete description and hence such physical quantities are called a vectors. |

3 | Uniform Motion | If a body covers equal distances in equal intervals of time |

4 | Non-Uniform Motion | if a body covers unequal distances in equal intervals or equal distances in unequal intervals |

5 | Speed | It is defined as the total distance travelled by the object in the time interval during which the motion takes place. SI unit of speed is meter per second. Speed is a Scalar quantity A body is said to have constant or uniform speed if it travels equal distance in equal intervals of time. |

6 | Average Speed | The ratio of total distance to total time taken by the body gives its average speed. |

7 | velocity | It is the rate of change of displacement of a body with the passage of time. Velocity of an object is measured in meter per second in SI units. It is a vector quantity a body is said to be moving with uniform velocity if it covers equal distances in equal intervals of time in a specified direction |

8 | Average velocity | The ratio of total displacement to total time taken by the body gives its average velocity |

9 | Acceleration | It is a measure of the change in the velocity of an object per unit time and mathematically it is given as Sl unit of acceleration is . It is a vector quantity A body has uniform acceleration if it travels in a straight line and its velocity increases by equal amount in equal intervals of time for example freely falling bodies |

### Equations of Uniformly Accelerated Motion

First Equation of motion

Second Equation of motion

Third equation of motion

### Graphs for Motion

Distance Time

**Velocity**

### Some Important Things

Speed is the distance travelled by an object in a given interval of time. | Velocity is the displacement of an object in a given interval of time. |

Speed is scalar quantity i.e. it has only magnitude. | Velocity is vector quantity i.e. it has both magnitude as well as direction. |

Uniform acceleration | Non- Uniform acceleration |

A body is said to be in uniform acceleration if it travels in a straight line and its velocity increases or decreases by equal amounts in equal intervals of time. | A body is said to be in non-uniform acceleration if the rate of change of its velocity is not constant. |

### Interesting Facts About Motion

S.No | Points |

1 | The fastest possible speed in the universe is the speed of light. The speed of light is 299,792,458 meters per second. In physics this number is represented by the letter â€śCâ€ť. |

2 | The first scientist to measure speed as distance over time was Galileo |

3 | The escape velocity of Earth is the speed needed to escape from Earthâ€™s gravitational pull. It is 25,000 miles per hour. |

4 | A speedometer is a great example of instantaneous speed. |

5 | Average speed tells us how quickly the body travelled the specific distance, but it tells us little of what happened during the time that the body was travelling the distance. It doesnâ€™t tell us if there was any speeding up or slowing down during the time. |

6 | Motion along a straight line is call is rectilinear and If the line is curved, the motion is curvilinear. |

7 | Kinematics is the branch of classical mechanics which describes the motion of points |

### Practice Questions

Question 1

An airplane accelerates down a runway at 3.20 m/ for 32.8 s until is finally lifts off the ground.

Determine the distance traveled before takeoff.

Answers

Answer:

Distance= 1720 m

Question 2

A Jeep starts from rest and accelerates uniformly over a time of 5.21 seconds for a distance of 110m. Determine the acceleration of the Jeep.

Answer:

Acceleration = 8.10 m/

Question 3

John is riding the Giant Drop at Canada. If John free falls for 2.6 seconds, what will be his final velocity and how far will he fall?

Answer:

Velocity = -25.5 m/s (-indicates direction)

Question 4

A race car accelerates uniformly from 18.5 m/s to 46.1 m/s in 2.47 seconds. Determine the acceleration of the car and the distance traveled.

Answer:

Acceleration = 11.2 m/, d= 79.8 m

Question 5

A feather is dropped on the planet other than earth which has very low acceleration due to gravity from a height of 1.40 meters. The acceleration of gravity on the other planet is 1.67 m/. Determine the time of feather to fall to the surface of the other planet

Answer:

Time= 1.29 s

Question 6

Rocket-powered sleds are used to test the human response to acceleration. If a rocket powered sled is accelerated to a speed of 444 m/s in 1.8 seconds, then what is the acceleration and what is the distance that the sled travels?

Answer:

Acceleration = 247m/

Question 7

Honda Activita accelerates uniformly from rest to a speed of 7.10 m/s over a distance of 35.4m. Determine the acceleration of the bike.

Answer:

Acceleration = 0.712 m/

Question 8

An Aeronautics engineer is designing the runway for an airport. Of the planes that will use the airport, the lowest acceleration rate is likely to be 3 m/. The takeoff speed for this plane will be 65 m/s. assuming this minimum acceleration, what is the minimum allowed length for the runway?

Answer:

Distance= 704m

Question 9

A BMW car travelling at 22.4 m/s skids to a stop Âˇn 2.55 s. Determine the skidding distance of the car (assume uniform acceleration)

Answer:

Distance= 28.6m

Question 10

A kangaroo is capable of jumping to a height of 2.62 m. Determine the takeoff speed of the kangaroo.

Answer:

Speed= 7.17m/s

Question 11

If Rahul has a vertical leap of 1.29 m, then what is his takeoff speed and his hang time (total time to move upwards to the peak and then return to the ground)?

Answer:

Speed= 5.03m/s, hang time = 1.03s

Question 12

A bullet leaves a rifle with a muzzle velocity of 521m/s. While accelerating through the barrel of the riffle, the bullet moves a distance of 0.840 m. Determine the acceleration of the bullet (assume a uniform acceleration).

Answer:

Acceleration

Question 13

A baseball is popped straight up into the air and has a hang- time of 6.25 s. Determine the height to which the ball rises before it reaches its peak. (Hint: the time to rise to the peak is one- half the total hang-time.)

Answer:

Speed =30.6m/s, d= 47.9m

Question 14

The observation deck of the tall skyscraper 370 m above the street. Determine the time required for a penny to free fall from the deck to the street below.

Answer:

Time= 8.69s

Question 15

A bullet is moving at a speed of 367 m/s when it embeds into a lump of moist clay. The bullet penetrates for a distance of 0.0621 m. Determine the acceleration of the bullet while moving into the clay. (Assume a uniform acceleration.)

Answer:

Acceleration (Negative sign shows deceleration)

Question 16

A coin is dropped into a deep well and is heard to hit the water 3.41 s after being dropped.

Determine the depth of the well.

Answer:

Distance= 57.0m

Question 17

It was once recorded that a Jaguar left skid marks that were 290 m in length. Assuming that the

Jaguar skidded to a stop with a constant acceleration of -3.90 m/ , determine the speed of the Jaguar before it began to skid.

Answer:

Speed= 47.6m/s

Question 18

A plane has a takeoff speed of 88.3 m/s and requires 1365 m to reach that speed. Determine the acceleration of the plane and the time required to reach this speed.

Answer:

Acceleration = 2.86m/

Question 19

A dragster accelerates to a speed of 112 m/s over a distance of 398 m. Determine the acceleration (Assume uniform) of the dragster.

Answer:

Time= 30.8s, acceleration = 15.8m/

Question 20

With what speed in miles/ h (1 m/s= 2.23 mi/hr) must an object be thrown to reach a height of 91.5 m (equivalent to one football field)? Assume negligible air resistance.

Answer:

vi= 42.3 m/s

Question 21

A Truck starting from rest moves with a uniform acceleration of 0.2 m/ for 2 minutes. Find

(a) The speed acquired

(b) The distance travelled.

Question 22

Match the column

Column A | Column B |

Speed | Scalar |

Distance | Vector |

Displacement | |

Acceleration | |

Velocity |

Question 23

Match the column

Column A | Column B |

22 km/h | 166m/s |

100 Km/h | 6.11 m/s |

10 m/min | 27.77 ml |

2 km/s | 83.33 m/s |

5 km/min | 2000 m/s |

Question 24

Study the speed time graph

Find following based on the graph

a) Which paths have constant speed?

b) When is the maximum speed reached?

c) When is the acceleration happened?

d) When is the deceleration happened?