9th Physics Chapter 2 Short Questions
9th Physics Chapter 2 Short Questions New book will be solved.
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2.1 Define scalar and vector quantities.
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Scalar
A scalar is that physical quantity which needs magnitude only to describe it completely.
Vector
A vector is that physical quantity which needs magnitude as well as direction to describe it completely.
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2.2 Give 5 examples each for scalar and vector quantities.
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Examples of scalars are distance, speed, mass, time, temperature, and energy.
Examples of vector are displacement, velocity, acceleration, force, torque and momentum.
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2.3 State head-to-tail rule for addition of vector.
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To add vectors, we apply a rule called head-to-tail rule.
Definition of head to tail rule.
To add vectors, we draw their representative lines such that the head of one line coincides with the tail of the other. The resultant vector is given by a single vector which is directed from the tail of the first vector to the head of the last vector.
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2.4 What are distance-time graph and speed-time graph.
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Distance-time graph shows the relation between distance S and time t taken by a body.
We take time t along x-axis and distance s along y-axis
Gradient (slope) of distance-time graph gives us speed.
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Speed-time graph shows the relation between speed V and time t taken by a body.
We take time t along x-axis and speed v along y-axis
Gradient (slope) of speed-time graph gives us acceleration.
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2.5 Falling objects near the Earth have the same constant acceleration. Does this imply that a heavier object will fall faster than a lighter object?
No, heavier object will not fall faster than a lighter object in the absence of air resistance.
Weight of any body will not affect the rate of free fall.
$$g\;=\;9.8\;m\;s^{-2}\;\approx\;10\;m\;s^{-2}$$
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2.6 The vector quantities are sometimes written in scalar notation ( not bold face ). How is the direction indicated ?
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With the help of axes, we can indicate the direction of vector, even its written in scalar notation.
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2.7 A body is moving with uniform speed. Will its velocity be uniform ? Given reason
If a body is moving with uniform speed, its velocity may or may not be uniform.
If a body is moving with uniform speed in straight line, its velocity is uniform but if its moving with uniform speed in curved path for example circle, its velocity will not be uniform because particle is changing its direction at every point.
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2.8 Is it possible for a body to have acceleration? When moving (i) constant velocity (ii) constant speed
If a body is moving with constant velocity, its acceleration will be zero because its neither changing speed nor direction.
But if a body is moving with constant speed and its direction is also not changing, there will be no acceleration.
If a body is moving with constant speed but its direction is changing, its acceleration will not be zero.
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Check! some useful link
9th Physics New Book Chapter 1 Notes punjab
9th physics 2025 chapter 2 numerical
You tube channel Class 9 New book Punjab boards Sir Najam
Home Page Notespunjab.com
