Q1
Assertion (A): The odometer of a car measures distance, not displacement.
Reason (R): Distance is the total path length travelled, which can differ from the straight-line displacement.
Choose the correct option:
Reason (R): Distance is the total path length travelled, which can differ from the straight-line displacement.
Choose the correct option:
📝 SolutionAn odometer records total path length travelled regardless of direction, which is distance, not the net straight-line displacement. R correctly explains why A is true.
Q2
A body moving in a circular path of radius $r$ completes one round; its displacement is:
📝 SolutionAfter completing one full round, the body returns to its starting point, so displacement (shortest distance from start to end) is zero, though distance covered is $2\pi r$.
Q3
Retardation (deceleration) means the acceleration is:
📝 SolutionRetardation is negative acceleration — it acts opposite to the direction of motion, decreasing the speed of the body.
Q4
Using $v^2 = u^2 + 2as$, find $v$ if $u = 0$, $a = 5\ m/s^2$, $s = 10\ m$.
📝 Solution$v^2 = 0 + 2(5)(10) = 100$, so $v = \sqrt{100} = 10$ m/s.
Q5
A quantity that has only magnitude and no direction is called a:
📝 SolutionA scalar quantity has only magnitude (e.g. distance, speed), unlike a vector which also has direction.
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Class 9 · Science
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