Matric Part 1/9th Class Physics Chapter 2 Long Question With Answer for Unit 2 Kinematics

Question # 1

Ans 1:
Speed: Distance covered by an object in unit time is called its speed. It is represented by v.
Formula: speed=distance covered/time taken
v=s/t
s=vt
unit: speed is a scalar
Ans 2:
Velocity: the rate of change of displacement is called velocity.it is represented by v
Formula: velocity= displacement /time taken
v=d/t
unit: velocity is a vector quantity and its unit is meter per second

Question # 2

Ans 1: Consider a body moving with initial velocity vi in a straight line with uniform acceleration a . Its velocity becomes vf after time t. The motion of body described by speed time graph by line AB. The slope of line AB is acceleration a. The total distance covere by the body is shown by the shaded area under the line AB. Third equation of motion can be obtained easily from the graph.
In speed time graph the total distance S travelled by the body is equal to the total area OABD under the graph. That is
Total distance covered by the object = Area of trapezium OABD
=1/2(sum of parallel sides)* Height
S= 1/2(OA+BD) * OD

Question # 3

Ans 1: Consider a body moving with initial velocity vi in a straight line with uniform acceleration a . Its velocity becomes vf after time t. The motion of body is described by speed time graph by line AB. The slope of line Ab is acceleration a. The total distance covered by the body is shown by the shaded area under the line AB. Equations of motion can be obtained easily from this graph.
In speed time graph the total distance S travelled by the body is equal to the total area OABD under the graph. That is
Area of OABD= S
Total distance S= area of rectangle OACD+ triangle ABC
Area of rectangle OACD= OA*OD=(length)* (width)

Question # 4

Ans 1: Solution: h= Vit+ 1/2 gt² putting values h = 0x5+1/2(10)(5)² = 0+125 h=125m Vf²=2500m²s-² vVf² = v2500m²s-² eg.. ( root cut with power ²) Vf = 50ms-¹ Ans..

Question # 5

Ans 1: Motion of freely falling bodies: Galileo was the first scientist to notice that all the freely falling objects have the same acceleration independent of their masses
Ans 2: Experiment: Galileo dropped various objects of different masses from the leaning tower of Pisa
Ans 3: Result: he found that all of them reach the ground at the same time
Ans 4: Gravitational Acceleration: The acceleration of freely falling bodies is called gravitational acceleration; It is denoted by g.
Value: on the surface of the earth, its value is approximately 10 ms-2
Ans 5: Sign significant: its value is positive when object move vertically downward. its value is negative when object move vertically upward

Question # 6

Ans 1: Kinematics: kinematics is the branch of mechanics which related to study of motion of objects without discussing the cause of its motion.
Ans 2: Rest: A body is said to be a t rest if it does not change its portion with respect to its surroundings
Ans 3: Motion; A body is said to be in motion if it changes its position with respect to its surroundings
Ans 4: Relative states of rest or motion: state of rest or motion of a body is relative
Example: A passenger sitting in moving bus is at rest because he is not changing his position w.r.t other passengers or objects in the bus. But to an observer outside the bus, the passengers and objects inside bus are in motion

Question # 7

Ans 1: Scalars Quantities: " A scalar quantity by its magnitude only." Explanation: A physical quantity which can be completely described by its magnitude is called a scalar. The magnitude of a quantity means its numerical value with an appropriate unit such as 2.5 kg, 40s , 1.8m, etc. Examples: Examples of scalars are mass, length, time speed, volume, work and energy. Vectors Quantity: " A vector quantity is described completely by magnitude and direction." Explanation: A vector can be described completely by magnitude along with its direction. It would be meaningless to describe vectors without direction Examples: Distance of a place from reference point is insufficient to locate that place. The direction of that place from reference point is also necessary to locate it. Examples of vectors are velocity, displacement, force, momentum, torque etc.

Question # 8

Ans 1: Distance: Length of a path between two points is called the distance between those points. Explanation: Let S be the Length of the curved path between two points A and B on it. Then S is the distance between points A and B. Displacement: "Displacement is the shortest distance between two points which has magnitude and direction." Explanation: Consider a body that moves from Point A to point B along the curved path. Joint points A and B by a straight line. The straight line AB gives the distance which is the shortest between A and B. This shortest distanced in a particular direction is called displacement. It is a vector quantity and is represented by d.

Question # 9

Ans 1: Position: the term position describes the location of place or point with respect to some reference point called origin
Ans 2: Distance: length of path between two points is called distance between those points
Unit: Distance is a scaler quantity. Its S.I unit is meter(m)
Ans 3: Displacement: the shortest distance between two points which has magnitude and direction is called displacement. It is represented by d
Unit: Displacement is a vector quantity and its S.I unit is meter

Question # 10

Ans 1: Acceleration: acceleration is defined as the rate of change of velocity of a body. it is represent by a
Formula: Acceleration=change in velocity/time taken
acceleration= final velocity- initial velocity/time taken
a=vf-vi/t
Unit: its S.I unit is meter per second square. it is a vector quantity
Ans 2: Positive acceleration: Acceleration of body is positive if its velocity increase with time. The direction of positive acceleration is same in which body is moving without change in its direction
Ans 3: Negative acceleration: Acceleration of body is negative if its velocity decrease with time. The direction of negative acceleration is opposite to the direction in which body is moving. It is also known as deceleration or retardation.