Physics : Kinematics : Book Back Important Questions, Answers, Solutions : Short Questions and Answer

__Kinematics | Physics__

__Short Answer Questions__

**1. Explain what is meant by Cartesian coordinate system?**

At
any given instant of time, the frame of reference with respect to which the
position of the object described interms of position co-ordinates (x, y, z) is
called Cartesian Co-ordinate system.

**2. Define a vector. Give examples**

The
physical quantity which is described by both magnitude and direction are called
vector. Examples : Force, Velocity, Displacement, Acceleration.

**3. Define a scalar. Give examples**

The
physical quantity which is described only by magnitude are called scalar.

Examples
: Distance, Mass, Time, Speed.

**4. Write a short note on the scalar product between two vectors.**

The
scalar product (or) dot product of two vectors is defined as the product of the
magnitude of both the vectors and the cosine of the angle between them.

**5. Write a short note on vector product between two vectors.**

The
vector product (or) cross product of two vectors is defined as another vectors
having a magnitude equal to the product of the magnitude of two vectors and the
sine of the angle between them.

**6. How do you deduce that two vectors are perpendicular?**

(i) The scalar product of two vectors . then these two vectors are perpendicular to each other because cos 90° = 0, then

**.** = AB cos θ = AB cos90° = 0.

Then the vectors and are said to be mutually orthogonal.

(ii)
The vector product of two vectors will have maximum magnitude when sin 90° = 1

i.e. θ = 90° then then the vectors and are orthogonal to each other.

**7. Define displacement and distance.**

**Distance :** Distance
is the actual path length travelled by an object in the given interval of time.

**Displacement :**
Displacement is the difference between the final and initial positions of the
object in a given interval of time.

**8. Define velocity and speed.**

**Velocity:** Velocity
is equal to rate of change of position vector with respect to time.

Velocity
is a vector quantity,

**Speed: **The speed
is defined as the ratio of total path length travelled by the particle in a
time interval. It is a scalar quantity.

Speed
= Path length / Time

**9. Define acceleration.**

●
The acceleration of the particle at an instant is equal to rate of change of Velocity.

●
Acceleration is a vector quantity. Its SI unit is ms^{-2 }and its
dimentional formula is

**10. What is the difference between velocity and average velocity.**

**Velocity **

1.
Velocity is equal to rate of change of position vector with respect to time.

2. It tells about the direction of motion of the particle.

**Average Velocity**

1.
The average velocity is defined as rate of the displacement vector to the
corresponding time interval.

2. The direction of average velocity is in the direction of displacement vector

**11. Define a radian?**

One
radian is the angle substended at the center of a circle by an arc that is
equal in length to the radius of the circle.

1
rad ≅ 57.295° (or) 1 rad = 180 / π deg*ree*

**12. Define angular displacement and angular velocity.**

**i)
Angular displacement:** The angle described by particle about the axis,
of rotation in a given time is called angular displacement. The unit of angular
displacement is radian. Angular displacement θ = s / r

**ii)
Angular Velocity :** The rate of change of angular displacement is
called angular velocity.

The
unit of angular velocity is radian per second Angular Velocity ω = dθ / dt

**13. What is non uniform circular motion?**

The
velocity changes in both speed and direction during the circular motion is
called non - uniform circular motion.

**14. Write down the kinematic equations for angular motion.**

i)
ω = ω_{0} + α t

ii)
θ = ω_{0 }t + ½ α t^{2}

iii)
ω^{2} = ω_{0}^{2 }+ 2αθ

iv)
θ = [ (*ω _{0}+ω*)

**15. Write down the expression for angle made by resultant acceleration and radius vector in the non uniform circular motion.**

Centripetal
acceleration = *v*^{2} / r

Magnitude
of resultant acceleration

a_{R}
= √ [ *a _{t}*

The
resultant acceleration makes an angle θ with radius vector

The
angle is given by tan θ = a_{t} / (v^{2} / r)

Tags : Kinematics | Physics , 11th Physics : UNIT 2 : Kinematics

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11th Physics : UNIT 2 : Kinematics : Short Questions and Answer | Kinematics | Physics

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